I’m going to be honest, I’m tackling another big one here, but it’s a question that many of the scientifically curious or simply not very busy readers of sci-fi novels may have come to wonder over the years.
How will human evolution change in the future?
As we have seen evolution is capable of creating some serious curve-balls (see blobfish, mantis shrimp etc) but do we have to worry about becoming massive-headed little green men as Roswell would have us believe, or even obese people resigned to little floaty chairs as seen in Disney’s W.A.L.L.E ?
Well in the words of the main man himself “endless forms most beautiful and most wonderful have been and are being evolved” (Charles Darwin!). This phrase is perhaps the most relevant here as it highlights a common misconception with human evolution that Darwin himself acknowledged 155 years ago, and yet is commonly ignored. Since Darwin observed the changes in animals over time, and experiments since have traced human evolution back to early primates it is easy to assume that evolution is something that happened, as this is the only way we can observe the process. But despite what some websites will delight in telling you, evolution is happening NOW, and there’s nothing you can do about it. In fact, by refusing to participate, you are probably doing the theory a favor.
Popular culture now influences our evolution more than survival:
So let us start with a saucy example, just to keep you all interested, Sexual selection, based on features like economic proficiency and physical attractiveness are becoming increasingly implemented selective pressures in human populations. This is largely because technological advances have removed many environmental pressures that would previously control our evolution, such as being able to run away from tigers etc. Whereas societal pressures have essentially started to fill in the gap as cultural aspects play an increasingly pivotal role in our evolution. Perhaps an example; the average 400lb male gorilla has a penis size of only 3cm! The average 180lb male homo-sapiens penis is 13cm (ambient temperature permitting), as it is believed that most ancestral hominid females largely chose mates based on their ability to satisfy them, a characteristic that has since amplified over time(you’re welcome). A fact you might like to point out to the next woman that claims she wants a “real man”. Unfortunately, the rumors about female breast size increasing are almost certainly the hopeful rantings of boob researchers, so shan’t be covered here (pun intended). As such, societal changes as a result of cultural influence are even more prominent than biological progressions and have been for the past 12,000 years!
Human evolution is dead, or is it?
Despite what I said earlier, there is good argument toward the theory that human evolution could have ceased altogether – genetic mutations that prove to be valuable, a longer beak, like Darwin’s Finches (or penis) are selected for in classic Darwinian evolution as they confer an advantage in mating, or survival to environmental conditions such as food. Typically however these mutations occur in small isolated populations that cause animals that are environmentally and geographically separated to diverge genetically – a process known (loosely in this sense) as speciation or “directional evolution”. However since humans now cover the entire earth and are extremely mobile – this form of evolution will simply be watered down in a mass of Mr and Mrs Average (not quite what Darwin had in mind), furthermore since the advent of modern medicine, around 98% percent of the population survive to become sexually active, removing Darwin’s “survival of the fittest theory.”
The term known as “panmixia” – gross crossbreeding and communication between colonies will likely lead to a phenotypically homogeneous population of 5’11 with a caramel complexion, black hair and brown eyes, not exactly inspiring – but a likely output in our immediate future.
Nevertheless, evolution is regarded as a highly contingent process, and if evolution were to re-boot, land mammals would almost certainly look completely different to how they do now, even if the environmental conditions occurred exactly as they have in the past, making all attempts to predict our evolution inevitably pointless…..what an informative blog!
In line with this unpredictability and rather excitingly (if you’re very patient or can freeze yourself long enough to see it) it is thought that because of these changes to classical evolution, human populations dynamics are now entering an entirely new state of genetic evolution.
The theory states that since population size is now so huge, while the chance of “loosing” an advantageous gene into the hubris of the vastly diverse gene pool is high, the chance that this mutation can occur many times in the same generation is also increased. This is because at each site in the genome there is the possibility for a genetic mutation numerous times throughout our lifespan – in just one individual, multiply this by 7,000,000,000 and you have an entire population that could over the course of a few generations become collectively and exquisitely sensitive so subtle environment changes. Therefore we could start to see the selection of newly advantageous genes (if they confer an increase of 5% more offspring each year) in 423 generations (10,000 years) to the point where 99.5% of the population now carry this gene.
While human technology may have collared most environmental pressures to the point where “Vogue” now has a greater impact on our evolution, there is still one aspect of environmental population control that we are increasingly vulnerable to – disease. As population density rises, and global travel takes off (aha) the potential for pandemic disease is higher than ever. Plus, since bacteria quickly become resistant to new antibiotics, pharmaceutical companies are no longer investing in their development because they’re “unprofitable”, how’s cultural evolution looking now eh?
But I digress, that last problem is likely to be overcome by the elephant in the room that I can ignore no longer, genetic engineering. While irreversibly engineering the DNA in one individual in every cell of their body, called “germ line genetic alteration” is currently illegal, the potential for this technology to eradicate harmful mutations, such as susceptibility to disease, or even to create transgenic humans resistant to disease is promising.
So rather than getting bogged down in the socio-ethical issues of human genetic engineering I thought I’d share a cool alteration (or potential modification) that we’ve done already…….in mice.
The adventures of PEPCK-Cmus mouse:
PEPCK-Cmus mouse was a genetically engineered mouse over-expressing an enzyme and transcription factor called phosphoenolpyruvate carboxykinase, specifically within its skeletal muscle tissues.
These mice could run for 5km (compared to 0.2km for normal mice) at a speed of 20 meters/minute, without stopping for rest and store more than 5x the amount of triglyceride in their muscle tissue than wild type mice. They have only marginal fat deposits compared to normal mice despite eating 60% more and contain more than double the volume of mitochondria, making them extremely hyperactive. Interestingly they lived 2 years longer than normal mice, extraordinary given that the average life expectancy is 2-3 years itself, the equivalent being a human living to 160 years old! Unfortunately the side affect did appear to be extreme aggression (to go nicely with hyperactivity) – all sounds a bit “I am legend” to me……
All in all it looks like our evolutionary future is going to be incredibly diverse, as long as genetic alteration is made available to everyone. Looking even further forward into the very distant future there is of course the idea of a post-human era, where humanity becomes a class II civilization, that is, we become planetary, leading to speciation between humans on different planets – if we’re not already interfaced with technology at this stage. Of course this is all science fiction, and so we finish this blog where we began, but if you don’t find it cool to think about, then you aren’t thinking about it enough!
Since the ideas I’ve tried to discuss here are so vast, if there’s anything people would like me cover in more detail, I would thoroughly enjoy writing a part 2 – it’s infuriating not being able to do it justice. In any case, indulge your intellect;
Hanson RW, & Hakimi P (2008). Born to run; the story of the PEPCK-Cmus mouse. Biochimie, 90 (6), 838-42 PMID: 18394430
Reed FA, Aquadro CF. (2006). Mutation, selection and the future of human evolution Trends Genetics DOI: 10.1016/j.tig.2006.07.005
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3327538/ – Are Humans Still Evolving? (Jay T Stock)