Jul 22 2009
Part One: Are humans still evolving?
By Fiona MacDonald
Zoology graduate and science writer Fiona MacDonald ponders what Charles Darwin might think of evolution in the modern world.
I often find myself wondering what Charles Darwin, the most famous zoologist of all time, would make of society and evolution today. It has been 150 years since ‘On the Origin of the Species’ was published and, although the same species walk the planet (give or take a few), a lot has changed.
Charles Darwin. Image: wikipedia
He argued each species had evolved in order to survive changing conditions, like a new habitat, predator or climate. Darwin’s ideas clashed with the era’s accepted view that every creature was created by God, exactly as they were. Yet 150 years on, scientists unanimously agree Darwin was on the right track.Darwin’s theories too have evolved as we learn more about Earth’s history and genetics, but his belief that every species, from tapeworms to tigers, originated from a few ancestors still underpins modern science.
Yet on days when it seems my greatest struggle isn’t surviving predators or hunting for food, but finding a seat on the train or hitting deadlines at work, I have to question whether Darwin’s theory of evolution can be applied to the modern world.
According to Darwin, natural selection should eliminate individuals who can’t adapt fast enough, leaving only the fittest to reproduce. As our population races towards seven billion people, it’s glaringly obvious reproduction has not been an issue.
The population keeps on increasing, but is natural selection doing its job? Image: Donncha, provided by Flickr
But are the fittest really passing on their genes? We’ve learnt to fight most of the pressures that should wipe out all but the select few.
• Disease – we’ve got facemasks, vaccines, drugs and antibacterial handwash to keep the majority of viruses and infections at bay.
• Competition for resources – we don’t compete with other species, we just take what we need with the help of modern agricultural practices such as irrigation.
• Drought/flood/volcano eruption – modern transportation means we can move somewhere more pleasant if our current habitat is spoiled.
Could all the technology we have spent years developing in order to prevent the loss of human life be theoretically hindering natural selection? Screw the fittest; we’re going to keep all the genes alive!
Penicillin was invented 46 years after Darwin died, and has helped millions of people survive infections that would previously have been deadly. Image: wikipedia
But it’s not just disease and disaster we’re interfering with, it’s sex as well. In the natural world, individuals are attractive because of their genetic makeup. Plants or animals with beneficial mutations or traits (like big horns, insect-attracting petals, colourful feathers) always get the most action because their offspring will have the best chance of survival and reproduction – and everyone wants to keep their genes alive!
Theoretically, this also applies to humans. Men are supposed to like women with curvy hips and big breasts because subconsciously they believe they will produce healthy children. Now that we can get breast implants and curve-creating liposuction, a man can’t count on his lust to lead his genes in the right direction!
A person’s smell is meant to indicate reproductive compatibility – the more attractive their scent the better the match, and the healthier the baby. But with the amount of fragrance most people douse themselves with I can’t imagine anyone could pick out a good baby-making match.
With dodgy genes being passed on simply because their pretty packaging has tricked our natural instincts, have humans moved beyond Darwin’s well-considered theory of evolution into some kind of random free-for-all? Or has the definition of ‘fittest’ merely changed?
All of these individuals have traits that make them attractive partners. When we fake these traits (far left image) are we cheating evolution? Image: wikipedia
The truth is, there are factors at work in modern society that Darwin could never have imagined. To be continued in Part II. (Which has now been published … here!)
Darwin’s legacy is being celebrated 200 years after his birth, in an exhibition in the Royal Botanic Gardens and The Domain. Find out more here.
I am a follower of the “idiocracy theory” namely that these days educated/successful/smart/etc people tend to reproduce late, and reproduce little, having one or two children, if that, late in life, when they have solidified their careers.
Bogans/trailer trash/plebeians in general have nothing better to do than have babies, and people duped into following a religion are often instructed by their church to have many babies, or at least not to use contraception.
The end result of this is that to whatever extent traits such as intelligence, rationality, work ethic etc are genetic, we are currently selecting for those who lack, rather than those with an abundance of, these traits.
(See http://en.wikipedia.org/wiki/Idiocracy )
This post is meant mainly in jest, but the point remains – does it matter that people with “better” genes seem to, under our current system of resource allocation, have few babies, rather than many? Or does it not matter at all? Are humans all genetically similar enough that what really determines our eventual phenotype is nurture, rather than nature?
Interesting post.
A few connected topics & thoughts:
In a nutshell: has our evolution led us to bend the laws of natural selection to our long term detriment.
A few heuristics :
- our own human weak genes can survive thks to medical progress,
- which has led us to clearly exceed the earth’s carrying capacity,
- etc
All of the above rolls up into the topic our our species leading the charge of the Sixth Mass Extinction.
Despite the trends and signs of increasing human population, scientists believe that we are in the sixth mass extinction wave. As opposed to the previous mass extinctions that have happened in the past, this one is the first mass extinction triggered by a species.
The five mass extinctions
First mass extinction : (c. 440 mya): End-Ordovician mass extinction
Due to climate change (relatively severe and sudden global cooling)
Caused pronounced change in marine life (little or no life existed on land at that time).
Second mass extinction : (c. 370 mya): End of the Devonian Period
May or may not have been the result of global climate change.
Marine species disappeared (eg brachiopods)
Third mass Extinction (c. 245 mya): End of the Permian Period
Could be due to complex amalgams of climate change perhaps rooted in plate tectonics movements.
Some evidence suggests that a bolide impact may have been the cause.
90% of species were lost.
Fourth mass extinction (c. 210 mya): End of the Triassic Period, shortly after dinosaurs and mammals had first evolved.Precise causes remains difficult to explain. The extinction affected reptiles and amphibians.
Fifth mass extinction (c. 65 mya): End of Cretaceous.
The most famous mass extinction
It wiped out the remaining terrestrial dinosaurs, molluscs and marine reptiles.
Consensus has emerged that this event was caused by one (possibly multiple) collisions between Earth and an extraterrestrial bolide (probably cometary).
Some geologists, however, point to a great volcanic event as part of the chain of physical events that disrupted ecosystems so severely that many species on land and sea rapidly succumbed to extinction.
Scientists argue that the sixth mass extinction began when the first modern humans dispersed to different parts of the world about 100,000 years ago. This process accelerated when humans turned to agriculture. Agriculture represents the single most profound ecological change in the entire 3.5 billion-year history of life. With its invention, humans no longer needed to interact with other species for survival, instead manipulated other species for their own use. They also did not have to adhere to the ecosystem’s carrying capacity, and so could overpopulate.
Humankind is using up almost half of all the energy available to sustain life on Earth, and this figure will only grow as our population leaps from 5.7 billion to 10 billion inside the next half-century.
The scientific community has reached consensus that 30,000 to 50,000 species are disappearing each year. This means that fifty per cent of the Earth’s species will have vanished in the next 100 years.
Such a dramatic and overwhelming mass extinction threatens the entire complex fabric of life on Earth, including the species responsible for it: Homo sapiens.
[...] were the natural selection factors driving evolution in Darwin’s day. Yet, as covered in Part One, it appears humans have managed to cheat their way past these factors using modern [...]