Charles Darwin posited that evolution happened over grand, geological timescales; the periods of time that make human existence, let alone lives, seem a blink of a planetary eye. But, of course, even over human lifetimes we have been able to witness the rapid, adaptive capacity of evolution.
We, here at the Trust, have previously reported on the fact that modern elephant are increasingly being born tusk-less. It is assumed that this is an evolutionary development shaped by elephant poaching. You can read more about this here. There is another well-publicised instance of adaptive evolution witnessed over a human’s lifetime, however.
The Peppered Moth, occasionally now nicknamed Darwin’s moth, is the most-publicised example of this. The Peppered Moth, we might remember from school, is a largely white, dotted with black, moth that once lived abundantly all over the British Isles. The lighter Peppered Moth was well-camouflaged from birds and other predators while it sat on the lichen covered trees abounding the country.
Amongst Peppered Moths, a not-infrequent mutation made a few, each generation, largely black with white markings. This mutation made the darker moths more visible amongst the lichen-covered trees of forested Britain. However, during Britain’s industrial revolution, the soot from working factories and industry’s large engines covered everything, including many trees, and killed off much of the lichen.
The darker moths, called melanic, were now better suited to their environment. Their population blossomed as that of their lighter toned cousins dropped. This happened over the course of an individual human being’s existence. The first melanic Peppered Moth ever found in Manchester was in 1848. By 1895, 98% of the city’s moths were melanic.
So, we have seen dramatic evolutionary changes within species, and, in this case, the change was adaptive.
We live in an era of rapid habitat and, even, climactic change. Will the world’s species adapt to us and our behaviour?
It’s a good question, one that needs asking for science’s sake even if the asking it may also be an attempt of humanity’s to shirk the responsibility of changing it’s behaviour.
Scientists at the Australian National University used the prolonged study of several species, 19 different populations to be exact, in order to get an accurate reading on how fast evolution actually works. Earlier attempts had been made to gauge the speed of evolution but this study was able to call on over 2.6 million hours of fieldwork in the shaping of its study.
When you’re measuring the rate of generational change, more is, obviously, better. Using the records – on births, on mating, on the reproduction and deaths of the studied populations – generations of researchers had collated information that could be used to generate what amounted to the net affect of changes in each species evolution.
The researchers at Australian National took the raw data and applied quantitative genetic models to it in order to arrive at their summary.
What they found was that evolution was taking place at a far faster rate than previously thought. Each species, they found, was 18.5% better adapted to its environment than the previous generation. Or, alternatively, each generation could better survive an 18.5% degradation of it’s environment.
That makes pretty reading for a conservationist. Conservationists of all animals, including elephant, are often beleaguered with doubt about whether any animal can learn to live in the world we change so rapidly. Elephant, with the large ranges they need to survive organically, are an extra worry.
But is that really so happy a tiding?
Despite the cultural differences visible between human cultures when one looks at our species from a global perspective, there are things that unite us all. One of those things is the fact that we are reluctant, often obstructively so, to lose what we have once gained.
The knowledge that the species which surround us may, after each generation, become better suited to the world we continue to change is comforting. And it may be used, by some, to argue that we need not change our worst practices and can continue on as before.
This does not, however, appear to be the case. A spokesperson for the research group that conducted the Australian National University’s study stated that environmental change is likely a more influential factor than genetic change is at impacting a species success. What’s more there are many other evolutionary factors that will impact generational adaptability.
If that doesn’t make absolute sense to our reader, consider the case of the Peppered Moth, again. The Peppered Moth, that incredible example of adaptability and the poster species for Darwin’s Theory of Evolution, is now, in drastic decline.
Despite that it survived the smog-filled skies of the planet’s first industrial revolution, between 1968 and 2000, Britain lost almost two thirds of its Peppered Moth population. The exact cause is as yet unknown and perhaps that is because there is no singular, exact cause.
The impact we are presently having on our planet is multifaceted. We are reshaping habitats, sometimes destroying them. We are recalibrating the chemical make-up of our oceans, even as we warm them. We’re warming certain areas, cooling certain others, and we’re filling even the hard to reach places with the waste of our existence.
The pressure we are now exerting on our planet, as it shapes environmental factors, is so complex and influential, it likely exceeds any species ability to adapt. And the truth of that statement is seen in the sheer amount of species that are presently listed as critically endangered by the IUCN.