Examples Of Known Or Suspect Human Reproductive Toxins: Fill & Download for Free

This is just not true. There is some very good evidence that humans have been evolving faster in the last 10,000 years. There is no evidence that humans haven’t been evolving in the last 10,000. Far from slowing down, human evolution has sped up in the past 40,000 years and has become 100 times faster in the past 5000 years alone. Evolution has accelerated in 1800 human genes, which encompass about 7% of the human genome.“The central finding is that human evolution is happening very fast — faster than any of us thought. Most of the acceleration is in the last 10,000 years, basically corresponding to population growth after agriculture is invented,”Recent acceleration of human adaptive evolutionIn large part how fast a population can evolve is related to the generations time. Humans, like elephants or orca whales, take a long time to have their first child and then only have one about every two years. Studies across cultures and time show that the average time from birth to having ones first child is among hunter-gather societies about 31.5 years for males and 25.6 years for females (although with a large variance), among less developed nations of 31.8 and 28.3 years, and among developed nations of 30.8 and 27.3 years respectively. This means evolution is slower for humans than for rabbits.Everywhere in the world, until just that tiny fraction of time that is the last 100 years or so, humans had very high infant mortality and high childhood mortality rates. In 1800, the health conditions of our ancestors were such that 43% of the world's newborns died before their 5th birthday. A century ago every third child died before it was five years old. In Sub-Saharan Africa, 1 in 4 children died in the early 1960s. An unknown number of embryos spontaneously miscarry because of various problems. It is thought that about 30–40% of all fertilized embryos are not carried to term. Any small trait that effected that would mean that that trait would become more common. Even today, most of the world population has very high infant and childhood mortality.Before 200 years ago, only a very few people moved long distances from their home and had children with unrelated people. The world population is thought to have been one and ten million people 10,000 years ago. 2 million is a good guess. Two thousand years ago the world population was about 300 million. Today is is over 7.4 billion. That increase in populations has meant rare mutations in isolated populations become more common in some cases.Humans are known to have less genetic diversity than our nearest relatives the chimpanzees and bonobos. If they had expanded so rapidly there would have been more variation to select form and thus more opportunities for them to evolve. Genomic Tools for Evolution and Conservation in the Chimpanzee: Pan troglodytes ellioti Is a Genetically Distinct PopulationNearby chimpanzee populations show much greater genetic diversity than distant human populationsHumans probably went through a population bottleneck that reduced genetic diversity. But our extreme increase in population since the invention of agriculture has meant an increase in variation. The number of new mutations increases as a linear product of the number of individuals and exponential growth increases the fixation probability of new adaptive mutations.Human migrations into Eurasia created new selective pressures in new environments on features such as skin pigmentation, adaptation to cold, elevation, and diet. Over this time span, humans both inside and outside of Africa underwent rapid skeletal evolution. Some of the most radical new selective pressures have been associated with the transition to agriculture. As people lived more densely after agriculture, virulent epidemic diseases, including smallpox, malaria, yellow fever, typhus, and cholera became important causes of mortality. Genes related to disease resistance are among the inferred functional classes most likely to show evidence of recent positive selection. Likewise, subsistence and dietary changes have led to selection on genes such as lactase and the need for lighter skin at high latitudes when grain is the main part of the diet instead of D rich game meats.As we have new genetic tools, more and more variants that have recently spread are becoming obvious. This research is only about 15–20 years old or so. In the coming years many more will be discovered. A recent study found 300 strong candidate regions for polymorphisms that have swept though populations. Genome-wide detection and characterization of positive selection in human populations.Here is from an article by Sarah Tishkoff, a geneticist and evolutionary biologist. She talks about some of the ways that humans have recently evolved.Examples of human local adaptations, each labeled by the phenotype and/or selection pressure, and the genetic loci under selectionHere are just a few of the ways in which humans have been evolving.One good example is lactase persistence. Most humans and most mammals stop making lactase after infancy. This means consumption of milk is uncomfortable as an adult. The ability to digest milk sugar (lactose) as an adult spread across Europe in the last 4,000 years.“The European LP-associated variant is estimated to be ~9000 years old, whereas the most common East African LP variant is ~5000 years old, which is consistent with archeological evidence for cattle domestication in the Middle East and east Africa. Sequencing of aDNA indicates that the European LP-associated allele was absent in early Neolithic Central Europeans and was at low frequency in late Neolithic Europeans, suggesting that LP spread recently (within the past ~4000 years) across Europe”The Inuit populations in Alaska, Canada, and Greenland have adapted to a cold and dark Arctic environment and a marine diet rich in omega-3 polyunsaturated fatty acids. Greenlandic Inuit show genetic signatures of diet and climate adaptation. Human whole body cold adaptationThe short stature trait is an example of convergent evolution in rainforest hunter-gatherer (RFHG) populations across Africa, Asia, and South America. Selection for small body size may be due to limited food resources, resistance to heat stress, immune response, and/or a trade-off between early onset of reproduction and cessation of growth.Genetic variants that confer resistance to malaria, include the sickle cell, α+- and β+-thalassemia–causing alleles at the hemoglobin loci, as well as variants at ABO, GYPA, GYPB, GYPE, and G6PD . All are younger than 5000 year old.The “G1” and “G2” genetic variants in the last exon of APOL1 are associated with chronic kidney disease, which is disproportionately common among individuals of African descent. These variants also confer resistance to human African trypanosomes (causing “African sleeping sickness”) by modifying the protein to lyse Trypanosoma brucei rhodesiense, a parasitic protozoa transmitted by the tsetse fly.There are three different adaptations in three different populations to live at high altitude. Living at high altitude (>2500 m above sea level) in regions such as the Tibetan Plateau, the Andean Altiplano, and the Semien plateau of Ethiopia can be deadly because of an insufficient supply of oxygen to vital organs (hypoxia). It is especially bad for those in utero and newborns. This drives evolution. Those with the genetic adaptations have more babies. The trait spreads over generations. Andean, Tibetan, and Ethiopian patterns of adaptation to high-altitude hypoxia.Human high-altitude adaptation: forward genetics meets the HIF pathway.Genetic adaptations arose in distinct populations in response to an increase in dietary starch intake in response to farming. There are a greater number of AMY1 gene copies in populations with a high starch diet (consisting of European Americans, Japanese, Hadza (African)) compared to populations with a low-starch diet (consisting of Biaka and Mbuti Pygmies (African), Datog (African), and Yakut (Asian).“Starch consumption is a prominent characteristic of agricultural societies and hunter-gatherers in arid environments…This behavioral variation raises the possibility that different selective pressures have acted on amylase, the enzyme responsible for starch hydrolysis.” Diet and the evolution of human amylase gene copy number variation.The ability to taste the bitter synthetic compound phenylthiocarbamide (PTC) is a highly variable trait in humans, and is correlated with both the ability to taste naturally bitter substances in food and food preference.Another answer here mentioned diving adaptations among the Bajau. They have spleens that are 50% larger and different genetics related to that. They have also differences in genes that control levels of CO2 in the blood and in the diving reflex. This would have been in the last 5,000 years. Physiological and Genetic Adaptations to Diving in Sea NomadsAnother group of diving people, the Moken, in SE Asia have superior underwater vision.“Their underwater acuity (6.06 cycles/degree) is more than twice as good as that of European children (2.95 cycles/degree). Our investigations show that the Moken children achieve their superior underwater vision by maximally constricting the pupil (1.96 mm compared to 2.50 mm in European children) and by accommodating to the known limit of human performance (15–16 D) This extreme reaction—which is routine in Moken children—is completely absent in European children. Because they are completely dependent on the sea, the Moken are very likely to derive great benefit from this strategy.. This extreme reaction—which is routine in Moken children—is completely absent in European children.”https://www.cell.com/current-biology/fulltext/S0960-9822(03)00290-2?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0960982203002902%3Fshowall%3DtrueHumans are adapting in some places to arsenic rich environments. Arsenic is acutely toxic to humans but is naturally present at high levels in groundwater across the globe. San Antonio de los Cobres (SAC), Argentina, is one such locale with high levels of arsenic yet has been settled by human populations for the past ~11,000 years. Arsenic metabolism involves methylating inorganic arsenic to monomethylarsonic acid (MMA) and subsequently to dimethylarsinic acid (DMA), which is less toxic.“We genotyped women from this population for 4,301,332 single nucleotide polymorphisms (SNPs) and found a strong association between the AS3MT (arsenic [+3 oxidation state] methyltransferase) gene and mono- and dimethylated arsenic in urine, suggesting that AS3MT functions as the major gene for arsenic metabolism in humans. We found strong genetic differentiation around AS3MT in the Argentinean Andes population, compared with a highly related Peruvian population (FST = 0.014) from a region with much less environmental arsenic.”The variants are likely under positive selection because they are embedded in long haplotypes in the SAC population and are at higher frequency than in neighboring low-arsenic groups with similar genetic ancestry.Human adaptation to arsenic-rich environments.Lighter skin tone has spread in populations in the last 10,000 years. Ultraviolet radiation (UVR) exposure is an important driver of pigmentation evolution in humans, with selection pressure for darker skin at low latitudes for UVR protection and for lighter skin at higher latitudes. A recent analysis of 230 ancient Eurasian genomes found that the allele associated with light skin pigmentation has likely reached fixation in modern Europeans from very low frequency during the Neolithic period due to strong selection pressure over the past ~4000 years. Genome-wide patterns of selection in 230 ancient Eurasians. Before agriculture humans in Europe for tens of thousands of years got enough D in their diet of wild game. When cereal grains became dominate in their diet they evolved lighter skin.At lower latitudes people need darker skin to prevent folate from being destroyed. If people do not have enough folate they have higher rates of neural tube birth defects, lower sperm motility, and slower healing. People who are distant from Africans such has south Indians have evolved darker skin for protection. Colloquium paper: human skin pigmentation as an adaptation to UV radiation.Samoans, have a mutation in CREBRF was found to be associated with BMI and fasting glucose levels. This variant is under strong recent positive selection, as evidenced by extended haplotype homozygosity and high allele frequency in the Samoan population but not other populations. Functional expression experiments in adipose cells showed that the Samoan variant decreases energy use and increases adipose fat storage, suggesting that this variant may have been adaptive in the past by increasing tolerance to periods of starvation A thrifty variant in CREBRF strongly influences body mass index in Samoans.A derived allele at the EDAR locus (EDAR370A) is significantly associated with hair thickness and dental morphology and is a target of recent strong positive selection in Asian populations. It also has a phenotypic impact on mammary and eccrine glands.Genetic resistance to Lassa Hemorrhagic Fever virus.A genome-wide survey of human genetic variation identified two genes biologically linked to LF infection among the strongest signals of recent human adaptation in West Africans. Further analysis of the LASV genome itself indicates that the virus has been circulating in West Africa for over a millennium. These findings-coupled with the high rates of disease, observed disease resistance, significant mortality and disability in affected individuals, and the widespread exposure to the rodent reservoir for the virus-suggest that LF is an ancient selective force, driving the emergence of genetic variants that confer resistance. Elucidating Genetic Determinants of Resistance to Lassa Hemorrhagic FeverA common inversion polymorphism at chromosome 17q21.31 is hypothesized to be under positive selection in Europeans because of increased fecundity of women carrying the inverted haplotype A common inversion under selection in Europeans.The Dutch are selecting for greater height in men.and average height in women. On average taller men have more surviving children in this society. Does natural selection favour taller stature among the tallest people on earth?In the United States, natural selection is working against environmental factors to actively favor shorter stature. Average height men and shorter women have more children over a lifetime. Shorter height in women is associated with a much earlier age at marriage and first birth in the United States, the increased length of the reproductive period contributes to higher reproductive success, despite shorter women suffering higher rates of child mortality. Natural selection in a contemporary human populationAlmost all the facial features that can be seen in skulls differentiate different populations such as nose shape and eye sockets and cheekbones have changed n the last 10,000 years. There is a young woman's skeleton found in Mexico for example from 12,300 year ago. She is genetically directly related to modern Native people in the Americas. She has the distinctive craniofacial morphology and generalized dentition of Paleoamericans. “the differences in craniofacial form between Native Americans and their Paleoamerican predecessors are best explained as evolutionary changes that postdate the divergence of Beringians from their Siberian ancestors” Late Pleistocene Human Skeleton and mtDNA Link Paleoamericans and Modern Native AmericansDetecting interregionally diversifying natural selection on modern human cranial form by using matched molecular and morphometric dataThe people native to what is now Mexico arrived there about 16,000 to 14,000 years ago. Today, populations in the north, the Seri, and the people in the south, the Lacandon, show the highest level of population differentiation, higher than between Europeans and Chinese populations in HapMap3. The Huichol and Tojolabal in Mexico have a difference similar to that observed between the Gujarati Indians and the Chinese in HapMap3. All these differnce have evolved form one small population who lived in the Beringia Plain for a few thousand years and then entered the Americas. Most of the changes would have happened after the development of corn, beans and squash agriculture, ie, less than 10,000 years. The Genetics of Mexico Recapitulates Native American Substructure and Affects Biomedical TraitsThere are also a number of genetic conditions that are suspected to be protective against disease when in the heterozygous condition.For example, Tay Sachs disease has been hypothesized that being a carrier may confer protection from another condition such as TB, explaining the persistence of the allele in certain populations. Carriers of the Tay-Sachs gene have increased production of the β-subunit of hexosaminidase and that the β-subunit is closely associated with increased host defense against mycobacteria. Additionally, cell surface bactericidal activity declined in the absence of β-hexosaminidase. It is therefore possible that β-hexosaminidase is cytotoxic to Mycobacteria tuberculosis, making the organism more susceptible to macrophage attack.Cystic fibrosis provides resistance to cholera, typhoid fever and other diarrhea illness. A person with misfolded CFTR won’t get cholera, while a CF carrier, with enough working chloride channels to breathe okay, but not enough to welcome toxin-spewing pathogens, suffers neither disease. The bacterium behind typhoid fever, Salmonella typhi, enters small intestine cells through CFTR channels. In people with severe CF the channels are too mangled to reach the cell surface. Bacteria can’t enter. Cells of CF carriers only let in a few bacteria. Protection against infections that produce the runs may therefore have kept CF around.Phenylketonuria. PKU is a classic “inborn error of metabolism.” A missing enzyme causes the amino acid phenylalanine to build up, devastating the nervous system. Carriers have excess phenylalanine — not enough to damage their brains, but enough to counter the effects of a fungal poison called ochratoxin A that causes spontaneous abortion. Thus, carriers will have more living babies in an area where this fungus exists. It isn’t coincidence that PKU is most prevalent in Ireland and Scotland. In the dampness of those lands, the Aspergillis and Penicillium fungi that produce the toxin grow on grains, which people were forced to eat during times of famine. Because pregnant PKU carriers were more likely to have healthy children than non-carriers, who suffered miscarriage due to the fungal toxin, the PKU mutation increased in the population. That’s natural selection. Evolution. It happens.People with Niemann-Pick C1 disease are protects from infection by enveloped viruses. It is a lysosomal storage disorder in which a faulty cholesterol transporter leads to abnormal accumulation of cholesterol within lysosomes. The Ebola virus apparently uses this transporter and thus its dysfunction impairs viral pathogenicity.Disorders of glycosylation, is a congenital disorder of glycosylation IIb and provides resistance to glycosylation-dependent viral infections (e.g., HIV-1, dengue, herpes simplex 2, hepatitis C, and influenza.Myasthenia gravis- Cholinergic antagonists may block rabies virus translocation. Some Peruvians may have evolved a natural resistance to the rabies as well. Antibodies found in Peruvians suggest natural resistance to rabies in local vampire batsHuntington’s disease sufferers tend to have more children. Symptoms associated with Huntington's occur later in life, after peak reproductive age. Huntington's strengthens the immune system during most fertile years allowing them to produce more offspring. The tumor suppressor protein p53, which maintains normal cell growth and is found at levels above normal in Huntington's sufferers. p53 not only reduces the incidence of cancer in those affected by Huntington's disease but by improving overall health may also contribute to increased offspring production. Studies comparing family members indicated that individuals with the disease had between 1.14 and 1.34 children for every child born to an unaffected sibling. Over time in a small population this would mean more offspring with the disease. Biologists Link Huntington's Disease To Health Benefits In YoungAs you can see from these few examples, (and many more will be discovered) the strange idea that evolution somehow stopped 10,000 years ago is really not supported by evidence. I am not clear why people want to think this. But it is not true and makes little sense. Human behavior in the last 10,000 years created radically new niches that humans lived in. The populations increased. As they increased new mutations increased. The human social norm of caring for the sick or weak means that useful mutations that might make one person sick but help others are able to spread. New diseases became endemic. Large differences in reproduction and child survival occurred. New foods were eaten. New places moved into.Adaptation must happen. There is no way to stop it. Mating and success in raising offspring is not random. Some traits will help and some will not. Some populations start from a small initial group and thus have different collections of traits. Some will be helpful. Some social systems will make some genes spread much faster than others. This will never stop. The idea that the way a few people have lived in the last 70 years with modern medicine and plenty of food will continue in a stable way for the next 5000 years is incorrect. People in 1850 England thought life would forever be like that. It was not to be. No culture or social system or language has remained the same or spread over the whole earth in a uniform manner. Ever. There is no reason at all to think evolution has stopped or can be stopped.Going global by adapting local: A review of recent human adaptationHuman evolution is still happening – possibly faster than ever

If you’re a consumer, you’re more powerful than ever.With so many independent brands springing up, and with increasing transparency online, you’re empowered to choose products from companies that share your values. You can decide to only buy cosmetics from companies that don’t test on animals, for example, or to support local businesses by shopping at your neighborhood farmers’ market.When companies respond to your values by creating products that are good for your health and the environment, it’s a wonderful thing. But sometimes, it’s tough to separate genuine brands from those that are marketing themselves that way to exploit a consumer trend.At NakedPoppy, the clean beauty startup I co-founded, we call this tactic “cleanwashing.” It’s based on the concept of “greenwashing,” a term coined in 1986 when environmentalist Jay Westerveld noticed hotels asking guests to reuse bath towels to help the environment—while in reality they wanted to save money on laundry costs and were doing little else to save the Earth.Unfortunately, the market is filled with brands that want your health and environmentally-conscious dollars—but don’t live up to the standards they imply.For example, in 2017, Walmart paid $1 million to settle a claim that its plastic products labeled “biodegradable” and “compostable” violated a California state law that makes it illegal for plastic products to be labeled “biodegradable” unless the brand explains how long it will take to break down on the label. And, in 2011, Fiji Water was sued over its claims that it was “carbon-negative,” when the company won’t actually get there until 2037.As clean beauty gains popularity with health-conscious consumers, cleanwashing is in full swing. This is why it’s important to know what to look out for.One example of cleanwashing involves misleading imagery. Some companies use “green” images on their packaging—flowers or leaves, for example— to imply that they’re “natural” when they’re not.Other companies create “no lists,” some with better intentions than others. “No lists” often include parabens, phthalates, formaldehyde and formaldehyde releasers, BHA, no this, no that—but there are more than 12,500 unique chemical ingredients in personal care products. Of those 12,500, there are known or suspected carcinogens, reproductive toxins, and endocrine disruptors among them. So a “no list” featuring 15 or even 50 chemicals isn’t all that reassuring. The substitutes can, sometimes inadvertently, be just as bad as the ingredients they avoid.With little government regulation of personal care products, you’re relying on brands to act in your best interest. There’s no standard definition of “natural” or “ clean,” and the term “organic” applies to food but is not helpful when it comes to makeup. This is because organic, food-grade ingredients don’t guarantee makeup safety and can’t ensure performance by themselves. Take clean liquid eyeliner as an example. No food ingredients are going to allow you to draw a sharp, jet black line, and safe, vetted preservatives are absolutely necessary to protect your eyes.At NakedPoppy, our definition of “clean beauty” is based on four core commitments:Your health. Every ingredient in each product we carry is evaluated for any negative health effects.Environmental health. Minimizing environmental impact is a top priority.Animal welfare. All of our products are cruelty-free.Community and social health. Fair labor practices, worker safety, and community outreach are important to us—we seek partners with positive values.Here are some things to look out for when evaluating whether a company is clean:Does the company publish their standards? That way, you can see if your values align and you can hold them accountable if they get off track.Are they clean at their roots? Every company has its DNA. Those born of a commitment to clean products are often coming from a more rigorous, dedicated place.Do they invest in the scientific resources necessary to vet properly? It’s tough to vet clean products without scientific review and having trained scientists stay on top of the latest research.Do they do the right thing, even when it’s difficult? At my company, NakedPoppy, our scientist noticed that one of our best-selling products contained Japanese honeysuckle, an ingredient that might be an endocrine disruptor. So we took it off the shelves. The decision put us at a disadvantage while other retailers continued to carry it. But there was no debate—customer health comes first. Luckily, the brand re-reformulated without Japanese honeysuckle and the product is back on our website.Are they constantly learning and open to feedback? NakedPoppy recently received an email from a woman who noticed an inaccurate statement in one of our blog posts. Here’s her message and our response:“I just read your blog post “ABCs of BHA and BHT” and saw the statement “Both BHA and BHT are banned for use in cosmetics in the EU.” Could you provide a reference for this statement? I cannot find either chemical on Annex II (prohibited) nor on Annex III (restricted) of the EU Cosmetics Directive. Looking forward to an explanation.”“I can’t thank you enough for bringing this to our attention. We have our scientists vet what we write, but obviously we’re human and can make mistakes. As soon as your email came in, we looked into it and you’re right. BHA/BHT are not yet banned or restricted from a regulatory standpoint—they’re merely on the European Commission’s list of suspected endocrine disruptors, the Prop 65 list, and the Substitute It Now list. We will make the adjustment to our post right away and appreciate you so much for bringing this to our attention.”Even the best clean beauty companies aren’t perfect. Science is a long way from understanding the health and environmental impacts of every chemical, plus the ways they change and interact with each other during the manufacturing process.It’s precisely because of these shortcomings, and the fact that the beauty industry is so lightly regulated, that you should seek out companies with a genuine commitment to clean products. These brands won’t be perfect, but clean beauty will be their core commitment and clearly defined. They’ll also be seriously invested in science and demonstrate their commitment to doing the right thing.

Funnily enough, I put a bit of thought into this a couple of years ago.What methods would be utilised by an alien aggressor to attack the Earth?Well it depends a great deal on what their goal and reasoning behind the attack is, if it is the reason is the total destruction of the human race with no care given to the planet itself then their methods would be entirely different to those used to eradicate the species while keeping the planet largely intact.Another factor that would come into play with this event would be time. On Earth, battles and invasions tend to be aimed at achieving the goal in the fastest time possible in order to reduce your casualties and not deplete your own resources and logistics. However, if you have anything up to two or three centuries or more in which to achieve your goal then you can use quite subtle and low key methods to quietly start the ball rolling and time will do a lot of your dirty work for you.Why would an alien race want to attack the Earth in the first place?1/ Elimination of the competition;This is the scenario whereby a race is expanding out into space and becomes aware of a potential competitor, possibly several centuries or even millennia behind them technologically but advancing all the same. A species that plans in terms of centuries will see the likely rise of that (and maybe other) competitors and so keep their edge by taking the competitor out of the game early. This may be especially true if the competitor is advancing rapidly (which we are).This is the most extreme form of basic natural selection and survival of the fittest (or in this case survival of the nastiest)2/ To handicap the competition;Similar to the first reason but this time the aim is not total destruction but just a serious enough blow to our progress that we are set back several centuries before we recover, perhaps to be hit again when that happens in order to keep us down.This is an extreme extension of industrial espionage taken to global proportions. The winning race gets the choice of the available resources and can effectively ‘name its price’ to any client races for services that no one else can supply (because the competition has been nobbled).3/ Religious reasons;This would be the most difficult aspect to combat, because unlike the previous examples, we would have no hope of ‘talking them out of it’ or pleading for mercy using logic, reason, moral or ethical arguments. A species’ religious belief strong and all-enveloping enough to compel it to start executing other races would have long ago thrashed out all the ideological aspects of their beliefs. All arguments against this behaviour would have been countered or all dissenters eliminated from the species. Every last one of them would be a religious zealot with no comprehension of an alternative to their pogrom.What could this belief system be like?, How about that they are the one and only intelligence in the Universe and all other species are just ‘animals’ to be used or eliminated at their whim.4/ Resources;This is actually one of the least likely reasons to attack Earth. Any resources that the aggressors might want (minerals, water, gases, volatiles etc.) would be far cheaper, easier and quicker to mine from asteroids in their own system. If they have the technology to travel to our system in sufficient numbers then they certainly have the technology to exploit these resources locally. It takes much more energy to lift a tonne of ore from the Earth’s surface into orbit than to take a tonne of ore from an asteroid with an almost non existent gravity field.Even food production is far easier in space than stealing it from a neighbouring star system. Hollowed out asteroids spun up for internal gravity and lit inside by fusion generators could grow all the food a planet would ever need.In fact the only type of mine accessible resources not available from asteroids and comets are fossil fuels, and even then some petroleum compounds are available in huge quantities from worlds similar to Titan. But you have to ask a basic question about this, why would a highly advanced species capable of travelling between the stars (which would without exception involved nuclear energy of some sort) then want to dig a load of coal to transport all the way back home, presumably so they can come home to a real fire in their living rooms. It just makes no sense at all.5/ Living space;This is a more realistic reason for wanting to take Earth. It assumes that the basic conditions are broadly similar to their own habitats. Although it is possible to simulate conditions of home in space (again the hollowed out asteroid spun for gravity and landscaped on the inside surface) this would not really house a large percentage of the population and is in many ways a poor second choice as a new home world, compared to open skies and secure natural planetary defences (atmosphere, magnetosphere, large enough biosphere to take some environmental damage inflicted by the occupants etc.)To further complicate this scenario, there would be several sub reasons for a species wanting new living space or a new planet to settle.A) They could be refugees fleeing a natural disaster on their home world.B) They could be fleeing an alien attack on their own home world and in doing so simply inflict the same fate on us.C) They could be one faction from their home world sent into exile (how many nations do we have that we would like to shoot into deep space)D) They could be colonists but the journey is one way, in other words they are utterly committed to taking Earth because they are now stranded in our system, this would be a battle for survival between them and us.6/ To spare us from a worse fate;What if another race knew that our world was doomed, or that a fate of such horrific magnitude were coming that it would be better to die quickly than suffer slowly (pick one of the previous suggestions). And what if this race were not in a position to assist or protect us from it. What would we do to a faithful dog or horse if we knew it had a terrible incurable disease or it was trapped somewhere and destined to die alone after suffering a lingering death.It is not beyond the bounds of possibility that this species could regard that is unacceptable (especially if it offends their religious or moral principles) and decide to carry out a ‘mercy killing’ of the entire race to prevent our suffering. This could also include their religious desire to ‘save our souls’ by separating them from our physical bodies. Maybe they would be in a position to rescue a select few of us but that would be little comfort to the rest who were left behind.7/ Slavery;Just because slavery is illegal in most (but not all) places on Earth there is no reason to believe that all species would discount it as an option for their workforce. In most countries on Earth slavery has been outlawed for many years but every country on the planet still has large slave like work forces, including every Western country. They just get labelled as migrant workers, underground workers, live in domestic staff or prison gangs.The argument used to counter this as an option of advanced species is that artificial intelligence and high level robotics would take up the heavy work rather than people. This assumes that artificial intelligence can ever be developed to that level. If you consider the economics of it, would a species spend trillions and decades trying to perfect AI when it might be cheaper and quicker to abduct and breed a slave workforce that is trainable, doesn’t require expensive maintenance, and is self perpetuating (you can breed further workers from a basic breed stock).Humans find enslaving other humans distasteful (mostly) but do we feel the same distaste about keeping and breeding horses, cattle, dogs, sheep etc.?) That could be the sort of evolutionary gap between them and us. The best we might get is that they are basically humane in their animal welfare standards.8/ Social Engineering;When you look at mankind, we are a fairly brutal species, we are greedy, spiteful, vengeful, self important and utterly thoughtless to others, including other species on the planet.A far more advanced species could regard our way of life or outlook as an aberration in need of drastic action. Would we as a species really listen if aliens arrived and began preaching a radically different style of government, morals or standards as the way forward? Some probably would, but many others would reject it or speak against it.There is also a risk that some of our less than ideal standards could actually flow backwards into their society, deliberately or otherwise. One of the things that humans are exceptionally good at is corrupting others.It could be deemed that some form of offensive action to eliminate key elements or infrastructure in society is needed to break things down a bit ready to rebuild in the way they want. There is a lot of truth in the adage that under adversity people pull together. It could be possible for a species to actually use this effect as a social tool to change how we do things.If this were the reason, would we necessarily want to resist it?The end product could be far superior to what we have now.9/ Revenge;Can we be absolutely certain that at some point in the distant past, perhaps even prehistoric times, we haven’t committed an atrocity against this species. This ties in with the debate as to whether the human race was ever technologically advanced in ancient times, ancient high tech civilisations, Atlantis etc.Or possibly revenge upon us for acts carried out against other species on the planet that we have forced into extinction. Again there are people in society who are quite prepared to kill others in retribution for animal testing, animal cruelty etc. We could be viewed as too dangerous to other up and coming species on the planet by a species that are effectively acting as ‘zoo keepers’10/ To let off steam;We humans still hunt for pleasure, they still subject animals to unbelievable suffering for entertainment or to satisfy deeper animal urges within themselves. There are many people in society that are more than willing to do the same to other humans. We call them criminally insane or psychopaths and lock them up or try to treat them.What if a species had decided the best way to safely vent these basic instincts was to organise large scale hunts or attacks on lesser neighbouring planets so that their own people don’t fight or damage themselves. This is the most extreme form of taking out your frustrations by smashing up an old chair or other object rather than attacking your neighbour, brother or boss. Afterwards you tend to have calmed down and feel somewhat drained. A good thing for your neighbour, brother or boss, not so great for that old chair that was home to a family of field mice.11/ Political reasons;Politics, even on Earth, is an extremely amoral activity, individuals, groups, governments and nations constantly using and abusing others, or even their own people, to gain credibility, status, power and influence at the expense of someone else.It is entirely possible that an alien government or nation may wish to use mankind as a political pawn in their bigger picture. Especially if that government is failing in some way and needs to raise its status. A common political tactic used in the past and even more so today is to demonise a foreign country, political group, ethnic group or religious faith. By turning on your own supporters hate for them and directing it carefully, you can divert their attention away from your own shortcomings.How much of an extension would it be to demonise a completely different species that may not be particularly appreciated to start with.It was done in Germany in the late 20’s, 30’s and 40’s to the Jewish and gypsy populations with devastating results and they were all the same species as us. It is done today by media and official reports painting a dim picture of some tin pot third world dictatorship. Then when enough saturation coverage has occurred it becomes so much easier to seek a mandate to send in the troops. While all the time nobody really looks too closely at how your administration has screwed up the budget or cooked the books.Nothing is a greater boost to your re-election chances than winning a quick, cheap and remote war.12/ Battle ground Earth;What is the best way to keep your troops at the peak of effectiveness, ready to be sent into any galactic trouble spot or to be used for your ongoing blitzkrieg through the stars?Regularly sending them into a nice contained, captive hostile planet for manoeuvres and battle practice with an unyielding (if somewhat battered) population.If the aggressors are sufficiently remorseless like this then the continuing loss of a few of their own troops will keep the rest on their toes and harden them to atrocities they may be called upon to inflict when needed elsewhere.This could be a truly horrific prospect because a passive beaten population wouldn’t be that effective a training tool. Therefore the best way would be to use just a little more military might than necessary to gain control, and then instigate a regime of unpredictability on the resident population.Initially batter the people almost into submission, then withdraw and give them a chance to partially rearm and gain confidence before again advancing and quashing the inevitable uprising. Repeat this pattern over a 30-50 year cycle and each generation thinks it is the first to get the chance to rise up. Further to this, in order to keep the humans hating their overlords enough to rise up the regime would have to brutalise them enough to make them explode. Humans will always eventually rise up against a brutal regime. The part of our nature that keeps us wanting freedom could actually be used against us in this way.13/ Selective breeding programme.This has certain similarities to the social engineering hypothesis except that rather than trying to move the bulk of the species toward some common social template. The attack is used to force evolution.Specifically if the attack is aimed at bringing out the most aggressive tendencies in us, it would mean it would have to continue for years to involve the whole population. This could systematically eliminate the most aggressive members of the species because as each wave of defenders is cut down new troops have to back fill. Over time the quality of the replacements will drop as those who have naturally held back are pushed to the front. Eventually mankind has only those naturally timid or least altruistic left and to continue the attack will mop up the last of the most aggressive members.Alternatively the attack could be used to separate out the aggressive people for a specific purpose, with the attackers sparing them and eliminating those that remain behind. The only real purpose for preserving these would be for use as a ‘press ganged’ troop body for further conquests. It is entirely possible that under this scenario, the troops used against us were themselves subject to the same ‘weeding process’ generations earlier. We would effectively become captive ‘attack dogs’ for the overlords.14/ New worlds to reproduce on.Now we are really moving into the realms of conjecture. We should stop thinking of alien species as being similar to ourselves, with individuals making their own decisions and leading relatively independent lives. Many animals on Earth are part of a hive community, primarily insects such as ants, termites and bees, but also to a lesser extent some rodents, birds and reptiles. In this community there is only one reproductively active female who is effectively mother to all the others. In higher animals this is achieved by pheromones within the hive suppressing the reproductive capacity of other females, they become sterile drones.There is actually nothing in logic to prohibit a social insect type animal community becoming intelligent and moving into space. However rather than treat each individual ‘worker’ or drone as a separate intelligent entity you should regard the entire colony as one intelligence, one creature.On their home world these hives would periodically send out fertile ‘Queens’ to set up new colonies. They would need fertile areas that will provide the basics that they and all their offspring would need. Over time the home world would not be enough but to set up on a new world would still need the basic resources for the new colonies to survive and flourish. Barren rocky moons would probably not be suitable as permanent homes and it could be the case that only life bearing planets similar to their own could be used.That would be bad news for us if Earth is about right.If they were only about the size of termites it might not be too much of a problem. But if the average size of them is somewhere in the metres range and the number in each colony is in the millions then they will need to take large swathes of territory and almost certainly would not be able to coexist with us on the same land.15/ The end of the experiment.Now we truly are getting to the extremes of conspiracy theories. Alien abductions, ancient astronauts and ethereal beings tinkering with our early development, perhaps millions of years ago, to observe our development to a point that is deemed ‘end of experiment’.We are close to being able to send significant resources and people over the next century or two out into the reaches of space. For any potential observing aliens this could be the crunch point at which they pull the plug on the experiment because it will become difficult to contain us on one planet. Rather than have to think of something to do with us or introduce us to the wider galactic community it might simply be easier to euthanize the whole population and examine the left over’s of our civilisation.16/ To create new marketsHow aggressive does a positive marketing strategy get? This scenario sees the attack as an extreme form of direct marketing to us. How about an attack that disables or destroys our ability to manufacture certain goods, or provide services to our own (and possibly other) species. Or some form of biological attack on our food crops would turn the entire planet into a captive market for these essentials. Imagine a world-wide rice crop failure. This plant is the basic staple diet of 2/3 of the world’s population. If it were to even partially fail, a global famine would rapidly set in and we would need an alternative source of food fast. If the attack were unannounced and we were simply to believe it were a natural disaster then the attackers could present themselves as ‘saviours’ just in the nick of time.The only thing with this scenario to consider is; what would they want as payment?METHODS;What methods might alien invaders use to either wipe us out or subdue us into surrender?As said earlier, it very much depends on their ultimate intention for Earth and how much time they have to carry this out in.1/ Send the bombers in!A massive heavy nuclear bombardment of all major population centres and industrial zones, the stock favourite of the film industry.Not actually that viable a method for several reasons. It would not wipe out a large proportion of the population quickly, it is very expensive to do (no matter how your economics work, a nuclear device is expensive and slow to produce, storing the number of warheads necessary would be a armoury officer's nightmare). The delivery systems expensive and may need to get within counter strike range to deliver all their payloads.Currently there are something like 20,000-22,000 available nuclear weapons on the planet. If they were all used in a total war the planet would be devastated, populations reduced to scavenger lifestyles and the ecosphere decimated. But it is unlikely alone to push us into extinction. That means the aggressor would have to send in the ground troops afterwards to mop up the remains. They would be vulnerable to resistance, radiation and other battlefield hazards.2/ Asteroid deflection;A far cheaper, simpler and decisive attack would be to nudge a large asteroid, perhaps something around the 200 km range, accurately into a collision course with Earth, or better still two or three large asteroids to make sure, all timed to hit within a few days of each other.The global damage would be enough to vaporise a large amount of the water on the planet and rob the planet of most of its atmosphere. Any survivors of the impacts would be dead within hours or days from secondary damage or breathing difficulties.The bonus to the aggressors is that they do not even have to announce their presence to Earth and risk incriminating radio transmissions leaking out of the star system to other races. The first we would know something bad was coming would be when the asteroids were spotted by telescopes and observatories. All they could do under those circumstances would be to announce the bad news and invite people to make their own peace. It would look like a natural disaster.3/ Attack our magnetosphere.Earth is only habitable to life because the magnetic field enclosing it deflects almost all the deadly solar radiation away several thousand miles above the top of the atmosphere.If the magnetic field were disabled, even for a few days, the Earth’s surface would be sterilised under a constant rain of high energy dangerous radiation. It would cause a rapid cancer epidemic of global proportions, including animals and plants. For longer periods the radiation would rapidly strip away gases from the top of the atmosphere and over several thousand years would again rob the planet of most of its atmosphere. It is strongly suspected that Mars would have a much thicker atmosphere if it had had a decent magnetic field.4/ Precision bombing.Selective, ‘precision bombing’ might be used as a selected ‘softening up’ process by attackers who are intending to take the planet with little damage and / or the resident population with minimal losses. Hitting, for example, 100,000 power stations, dams, transport hubs, military establishments and manufacturing centres, especially if it is done with clean nuclear weapons or ultra high efficiency conventional weapons (fuel air explosives, area denial mine scattering warheads etc.). Exploding nuclear warheads in the high atmosphere to disrupt our computer systems, or even dropping masses of robotic hunter-killer devices that would drive the population away from vital areas is possible, especially from space where no target is beyond your reach.However this is again expensive, may be of limited effectiveness in the longer term and exposes your own forces to counter attack risks. The problem would be made worse by the population being dug in and defensive when you finally have to go in on the ground.This scenario would be in the realm of aliens that are not actually that much more advanced than we are.5/ Sabotage by alien infiltrators.Body snatchers, aliens in disguise, invisible aliens, mind controlling aliens. They have all been used many times in science fiction, usually because the special effects are cheaper and it plays on an innate human fear of parasites.The truth is that it would be unlikely to work and probably quite comical if anyone tried it. Can a human which the best make up and specialist guidance possible successfully infiltrate a troop of baboons and not be noticed? And these are animals that closely related to us and are not going to try and expose you with complex questioning. It is likely that we are more closely related to and resemble a lobster than an extraterrestrial.Even if the deception could be pulled off it exposes their advanced agents to constant risk of capture or death and relies on an agent being able to keep up an utterly alien (to itself) performance for days, months or even years without breaking cover. This would be even more difficult if they have to maintain contact with their forces or our security services got even so much as a whiff of the programme.6/ Putting us in the shade;Take several large carbonaceous asteroids (carbon rich) and nudge them into a suitable orbit around the Earth. These asteroids are naturally much darker in colour then the usual iron rich or ice asteroids. Then you systematically start breaking them up first into rubble and then into dust using shaped explosives and directed energy weapons and tools. As you work the dust spreads along the orbital plain in a carefully pre calculated way until you have a dark light-obscuring ring around the Earth. It won’t block all the sunlight out, but it could reduce light sufficiently to make even a cloudless day no brighter than dusk. The effect would very soon be failed harvests, power shortages, changed weather patterns due to the reduced heat absorbed into the atmosphere, and in all likelihood a rapid onset of glaciation and advancing ice sheets.Again it won’t totally wipe us out but could reduce our numbers and our ability to fight back, especially when we start using our weapons on each other as the famines and shortages start to bite, which we inevitably would.This is another scenario where the aggressors could set the ‘weapon’ in place and leave it to take effect while they may not need to return for several centuries.7/ Biological warfare.This is actually moving to the more realistic prospects. Biological technology is likely to be one of the areas that aggressors could be centuries at least ahead of us on. Developing a suitable highly infectious virus that could be released into the environment might be a fairly straightforward affair, even developing one that left all other species untouched. It would require far less energy and resources to transport the raw materials to our Solar system and could be developed ‘on site’. Delivery systems could be as simple a drop canisters from orbit or abducting a few of the population, infecting them whilst they are sedated, then returning them and thus creating a select group of ‘typhoid Mary’s’The virus could be fast acting like a doomsday flu virus. This could eradicate the majority of the population within a few months or certainly within a decade.It could equally be something that acts more slowly, such as HIV. Such a disease not only kills steadily over a number of years (thus allowing the remaining population to clear the dead and not allow the build up of corpses) but also acts as a deterrent to further procreation. Currently there are estimated to be something like 40 million HIV sufferers world wide. This is likely to be an under estimate. Perhaps 20 million have died over the 20 years it has been recognised.However more of the population are practising safe sex than might otherwise have done so, this has led to a revision in the estimates of the peak population downwards. It is likely that more people have simply not been conceived than have died from HIV. In other words by this date the disease has probably removed more like 50 to 80 million people from the population and will continue to do so.What would be the effect of newer more virulent strain that is perhaps more infectious than at present. It would not be too much of a leap to guess that 100’s of million might be infected and the birth rate could easily drop significantly below the death rate as people just don’t want to go near each other. There is actually a fairly narrow band in the birth rate figures above which the population spirals out of control and just below which it begins to collapse. We are just in the upper part of that narrow band meaning our population is rising but not terrifyingly fast. A drop in the birth rate of just a few percent could tip us into a rapid population decline.A scenario like this might take over a century to show significant losses in the population but for an alien race that could station robotic observation platforms and retire to let time do the job, this might not be a problem.Another form of biological warfare could be to attack not us, but one of the many other species that we rely upon, such as a food crop like wheat or rice. An attack like this would cause widespread famine, malnutrition and internal warfare as countries and even territories fought for dwindling food stocks. Although this in itself might not kill us all off it would again be something the true aggressors could sit back and watch. Over time our numbers would reduce through starvation and warfare, those that survived would have a significantly reduced ability to fight off a second wave attack.8/ Self replicating robots;You have a standard design robot that can carry out military actions, refuel itself in the field and using raw materials in the field produce more copies of itself to continue the process.These devices have actually been long considered as permanent explorers, almost a form of machine life in themselves. They are also known as Von-Neumann machines, after the philosopher that considered them, although he was not looking at them as a weapon of war.Imagine an initial drop of perhaps 100 of these robots across the globe, their first objective is to build a further 100 each before starting their blitzkrieg. We might be able to fight and destroy some of them (maybe they are as tough to dent as the latest tank designs) but could we keep the fight up permanently? Perhaps NATO could repel an advance of 10,000 ‘super challenger’ tanks initially. But a battle like that would deplete our weapon stocks faster than we could replace them. If the numbers of advancing machines were growing ever larger because they can rebuild faster than we can destroy them you can see that over time they would overrun our defences. Human wars are often turned because one side manages to cripple the manufacturing ability of the enemy. One side cannot build any more tanks because the factories have been destroyed. But what if they didn’t need factories because each tank can produce another just like it every week just by clawing in the smashed wreckage it comes across or even the soil and rock of the countryside around it.It is conceivable that just one of these machines initially dropped somewhere could cause the same problems. It lands somewhere remote and quietly starts copying itself until there are sufficient numbers to carry out the war plan. If we didn’t find it and destroy it in time then this same scenario could ensue.Robots don’t have to be big to accomplish this same objective, instead of the machines being like ultra tough tanks, imagine they are the size of a house fly. Still able to copy themselves, including the ability to generate a small amount of nerve toxin from common compounds in the environment (Nerve toxins such and Cyanide are simply compounds of Nitrogen, Hydrogen, Carbon and other similar common elements. All of these form part of our atmosphere).With perhaps 10 million of these nasty little ‘knatbots’ flying about seeking out humans we could be in serious trouble. A knatbot simply lands on a person and injects them with cyanide then flies away to leave the victim to drop dead within a few minutes. It would be almost impossible to keep them out because any door, window, air duct, pipe or even just a gap in the brickwork would give them entry to any building, even underground facilities.Every week there are another 10 million poison knatbots buzzing around, each capable of killing perhaps 20 people and copying itself. Within a few weeks or months at best we could find our species virtually wiped out. This form of chemical warfare again could be very cheap for an aggressor. The energy and costs required to send a tiny robot perhaps weighing only fractions of an ounce across the vast stellar distances could be minimal compared to the payoff of a planet ready for your people following on at slower speeds.The robots would not pose a threat to the aggressors themselves because they could simply be ordered to destroy themselves or assemble in one place and cease replicating.Our only defence against self replicators would be to cut into their instruction delivery system, decode and decrypt the hierarchy and try to countermand their orders.9/ Psychological warfare;What is more frightening and therefore far more effective at reducing your ability to defend yourself? An enemy you know and understand, or one that you know next to nothing about, no idea of strengths, methods, reasons, objectives, weaknesses, position. You don’t even know what they look like, sound like or how they will deal with you.Scary huh. Now extrapolate that to a global scale such as this scenario;Fragments of information start getting into the general population that an invincible and utterly alien force has designs on our planet, that they have exterminated other worlds as they head towards us, that they may already be here working among the population.It doesn’t matter if most of that is not true, with enough suitably directed hints and clues, a few well placed ‘incidents’ and the odd sighting could have large pockets of the population accusing others of being involved. Governments could easily find themselves the target of suspicion as sympathisers or even as aliens in disguise themselves.Within months or even weeks basic government could break down and murder, suicide, accidental death and infighting could start whittling down our numbers and defence capability without the true aggressors ever firing a shot. It could be the ultimate challenge for an alien ‘spin doctor’.Another form of this could be ‘friendly persuasion’ approach. This takes the form of formal contact with Earth by the approaching aliens, opening a dialogue and building up a good sound rapport until they arrive. The whole world has known they are coming. Then the aliens dispatch their most eloquent speakers with a carefully researched and overpoweringly convincing argument as to the futility of resisting them. With the use of deep philosophy, sound and considered reasoning and the ability to capture crowds better than some of our best leaders and speakers they could literally talk us into laying down and accepting the inevitable.If you think that is impossible then think again. Religious and political crackpots all over the planet regularly talk hundreds of followers into ritual suicide or acts of violence so depraved you could not imagine how anyone could do them.Is it possible to come up with a fundamental argument that life as a human is so pointless that simply to hear and inwardly digest it is enough to have you reaching for the sleeping tablets or maybe even enough to cause you to drop dead from the futility of it all? It might be for a species that has had perhaps centuries to fine tune their arguments. This scenario actually makes more sense to those who have ever seen the Monty Python sketch entitled ‘the funniest joke in the world.’10/ Squatters rights;Here is an interesting thought. What would the world do if a new intelligent species of animal were conveniently discovered in some partially explored corner of the planet? Perhaps a set of remote islands or deep in rain forest or halfway up a mountain in Africa? It could be as intelligent as us (or even more so). Most likely we would immediately jump to protect this new, undiscovered ‘child of Earth’. Maybe even try to encourage this new species to expand its numbers to protect it from extinction.This is great, and all very noble. However, what if that species is simply a colony quietly transported there recently with the express intention of fooling us into thinking that it is indigenous to the planet. We always think of a new planetary colony for us almost as an outpost for our society. But that does not necessarily follow. If we are simply aiming to increase the places that humans exist and are not bothered that our history and technology go with these colonies then it could make perfect sense to dump a sufficient number of reproductive humans in a place and hope they will eventually make it. When playing the numbers game a few generations of suffering and individual losses may be acceptable. This applies even more so if you are aiming to use the resident population as unwitting hosts.Those familiar with the habits of cuckoos will recognise this trait.How about even more outlandish thoughts;What would we do if an alien fleet arrived at Earth and claimed that they are the descendants of the first intelligent species that evolved on Earth millions of years before we did?There are theories about possible intelligent beings that evolved from reptiles around when the last of the dinosaurs were still alive. Many stem from the interesting fact that species are currently going extinct at the same rate now as at the time the dinosaurs went to the wall. Was it a massive asteroid impact, or volcanism that killed them off, or was it the rise of an intelligent species of reptile that systematically built up cities and roads across the planet and just took the habitat away, only to be wiped out themselves by that asteroid (or warfare amongst themselves) If true, did some of them flee Earth and are now looking to return?Just how generous should we be to them if they use the argument that they were here first?If true they would already be perfectly adapted to the conditions on Earth (bad news for us).What if they are lying about it and we can’t disprove their story. We could spend years arguing about the correct course of action while they slowly endear themselves to the general population. Could governments really threaten to attack them if they have become familiar faces (even friends) to society for 20 or 30 years. Most likely that would see administrations voted out before any shots were fired.What would we do if an alien fleet were to start landing and setting up home in a rural part of the world and yet made absolutely no aggressive gestures whatsoever, perhaps even totally ignored us while they started building. There would be a significant period of hand wringing while governments tried to persuade them that it would ‘nice to ask next time’ as well as most governments wanting to keep them around to study their techniques, them and their society.We could find the ‘invasion’ is more a case of us getting steadily crowded out with more aliens arriving each week.An alien family simply arrives on your land, starts building their shelters and fencing off bits of land around them. Do you complain directly to them simply to be ignored? Who do you call next, the army or the police? The ultimate traveller invasion.11/ Hijack our own genes;Possibly the cheapest and maybe only method of moving your species between star systems is to just send your genetic blueprint. It could travel by radio, or coated on thousands of asteroids, or in tiny high speed craft perhaps only a few grams in weight. A million DNA molecules will still only weigh in at fractions of a gram and could be frozen to preserve them for thousands of years.Little craft like these could be sent out in the thousands, even there millions, in all directions to drift through the galaxy and only activate if they come close to a viable world. Even though almost all of them would never find anything suitable and drift forever, a hit rate of say 10 good planets for every 10 million craft you send out is a good return.The craft falls into the atmosphere and scatters its activated genetic material into the biosphere to be absorbed by the local flora and fauna. If the DNA is a dominant strain it would steadily dominate the subsequent offspring of whatever species it bonded with. It is not a case that any plant, insect, fish or fungus would start sprouting aliens because most would be too different from them to work, the most likely outcome would be cancer in the species.However if the genes bonded to a sufficiently similar species, perhaps further up the evolutionary ladder, maybe of a similar size and build to them, then the genes might take.If that species happens to be us then we could see an initial increase in mutations followed by a settling period them each generation of kids looking a little more alien to their parents.Of course it doesn’t have to be humans that would suffer this. Most large apes, maybe other large mammals etc. could also start producing alien offspring too. We could end up with an entirely alien biosphere with alien animals, plants and people.There are theories that state that humans are already the result of this and that at some point in the past our genes were put into some basic plains ape running around at the time, and that without that intervention it would never have evolved intelligence.This again could be a strategy if you are purely playing the numbers game.12/ ‘Soft’ weapons;The military and police forces around the world are nowadays always looking at methods to subdue individuals, groups or crowds without actually killing them. So called soft (and usually unpleasant) weapons. Such things as tear gas, tasers, water cannons etc. were the original soft weapons and are still used in many parts of the world. However there are newer and more effective ones in development. Some are sound weapons that drive people away from certain areas because they can’t stand the noise. There are infra-sound weapons that can affect people’s internal organs, cause them to lose control of their limbs or bowels (lovely!) Or even to black out. Gases that can knock humans out for hours or days and totally blank their memory. Substances that can render people highly susceptible to suggestion or hallucination.Certain electrical patterns or radio frequencies can also affect our mental abilities.How much of a technological leap is it for an alien aggressor to poison our water supply rendering us as mindless drones until they can establish control on the ground. Zombies in Haiti have been found to be drugged by powerful natural hallucinogens that do just this. To most people they appear to be dead.What about a radio signal that has a similar effect, broadcast from hacked into radio transmitters? The effect does not even need to be to take over our minds, what if the effect were simply to make us feel drained, or queasy, or to temporarily blind or deafen us, or to heighten our nerve sensations so much that just to touch something causes pain. How much could we do to defend ourselves if that ever happened?13/ Invite us to leave Earth;Trojan horses, software worms, malware. We’ve used them all.Perhaps the easiest way of doing things is not to attack at all but to contact Earth from afar, supply technical knowledge via radio on how to build advanced space craft and supply strong reasons for the race to up sticks and leave Earth en mass. How long would it take? Centuries at least. How much cost and effort is there to the aliens? Just the cost of a few ‘long distance phone calls and Emails’ Once the human race is safely space bound and moving off to pastures new the aliens could quietly sneak in behind and set up shop on the planet’s surface.This is not actually a very likely scenario because many humans would not leave, and the act of supplying technology to them would in itself increase mankind’s ability to defend itself.A more likely version of this scenario would be to supply technical knowledge with an extremely well hidden ‘booby trap’ contained within the information, almost like a Trojan horse worm or virus. However this one sees human society constructing devices and machines, perhaps new forms of power generation, to the specifications supplied only to find they have actually constructed some form of planet busting bomb. Or even stranger, some form of inter dimensional gateway allowing the attacking hoards to immediately flood out of the secured ‘beach head’.14/ Take the high ground;Why orbit the Earth and try to mount an attack from orbit when you can happily set up on our own natural satellite, the Moon, out of harms way and start firing at us with long range weapons.Initially I considered the possibility of quarrying out rock and firing it at us by electromagnetic catapult. But this would be unlikely to work as the missiles would burn up in the upper atmosphere. Besides we are being hit by rocks this size daily anyway and seem to be getting along fine. They only pose a slight hazard to satellites and orbital traffic.But how about directed energy weapons such as lasers, particle beams, neutron rays etc. A focused laser in the 10 megawatt range fired from the lunar surface with a beam divergence of only a few metres by the time it hit Earth would be an extremely devastating weapon wherever it struck. Some of its energy would be dissipated by the atmosphere but only to the extent of superheating the air and causing gigantic thunderclaps and shock waves. At present we can produce weapons of this magnitude but only be chemical reaction the lasts for microseconds and then the laser equipment has to cool and be reloaded and primed. How about a cannon that maintain a fire rate of ten one second bursts a minute indefinitely? That is a lot of damage. One burst would most likely cause the same damage as a small nuclear device due to the vaporised material and shock waves. On the Moon they could construct hundreds or even thousands all over the Earth facing surface. The only respite we would get would be when the Moon drops below the horizon.It doesn’t actually have to be a laser either. How about a large focused reflector for sunlight. With careful focussing, ten square kilometres of sunlight could be focused to converge just at the Earth’s surface over an area of only a few dozen square metres. The focus point would just travel along as the Earth turned under it burning everything it travels across. The beam would be constant too. The only respite would come when the Moon turns enough to move the reflector out of the Sun’s view. We would have about ten to twelve days rest before it started up again.What defences are there to these? Pure and simple we would have to send the troops there, with the strong possibility of a lot of them being vaporised by those same weapons long before they reached the Lunar surface. The reflector weapon may be a little easier to deal with, one or more nuclear missiles directed against it could rip enough of it up to reduce the reflection capability, even a near miss might scatter enough Lunar dust over it to achieve the same result.15/ Stir up trouble between us;In most of these scenarios I have assumed that most Nations on Earth would band together for the common defence of Earth. But in all honesty most countries wouldn’t give two hoots if a thoroughly unpleasant neighbouring country were to suffer at the hands of someone we consider a ‘friend’. Or how about that friend offering us the technical know how and or some logistical support so that we can beat the other side hands down. Would the USA be so reluctant to take on the Russian Federation, China or even North Korea if they were in possession of knowledge that would protect their interests from counter attack (how about a near 100% perfect missile shield) The same applies the other way around. Would North Korea, China, Zimbabwe or Nicaragua hold back from wiping out their neighbours if they thought there would be no comeback?The alien aggressors need only to promise or supply technical information for ‘super bombs’ etc. to one side only (or even a select few countries) and sit back after assuring their ‘customers’ that victory would be in the bag.The subsequent war would do a lot of the necessary damage for them without any need to enter the contest themselves or construct or deploy any weapons themselves. They then just do it again with a different weapon until we have whittled our numbers down enough to something they can deal with.In fact, they don’t even need to just supply one side. A better effect if by giving both sides various pieces of weapons knowledge without the other side knowing and let them hammer away at each other taking millions of lives and defence capability out of the subsequent equation.Again this is a common human trick, used every day on school playgrounds across the planet by people who love to simply stir up trouble and start fights.They don’t usually grow out of it.Last word:Well I hope all this has cheered you up no end, as it happens I don’t actually think we are the target of some impending alien attack. It’s just a bit of fun, a thought experiment to demonstrate that as we expand away from Earth we need to start ‘thinking outside the box’.Don’t have nightmares, and watch the skies.