Photo: Pixabay
Humans are already living longer and it's likely - we'll be taller, more lightly built and less aggressive. But how well are we adapting to this modern world and what other changes will there be?
Perlina Lau talked to Dr Nicholas Longrich a Senior Lecturer in Evolutionary Biology at the University of Bath about why predictions about humanity's future path matter.
Longrich said because people making predictions do not know what will happen - it is useful to consider a wide range of different possibilities, and then to adapt that thinking as new information arises.
"One thing you can do is you can look back at how things have evolved recently, and just kind of extrapolate that forward. One of the best ways to predict the future is to look at the past....
"If you look back over the past 10,000 years what you find is that it's a bit unnerving but our brain size has decreased, we've actually lost grams of grey matter ...exactly what's happening there isn't entirely clear. It could possibly be that as we're less physically active we're losing bits associated with motor coordination. Extrapolating forward, it's quite likely we'll actually evolve smaller brains not larger ones."
Photo: 123RF
Humanity's collective journey from the past gives some clues about how our bodies might change, too.
"We might become ... less muscular, because we're not relying on physicality, brute force," Longrich said.
"We don't have to go out and hunt our food any more. We don't have to go out and till the field any more, we're increasingly working with our minds or maybe our fingers on a keyboard, rather than our bodies.
"The counter argument is that different forces come into play to the extent that natural selection is less and less important, and sexual selection becomes more and more important - mate choice. Who do we choose to mate with? And if there is a strong selection for a more muscular physique, if people find that more attractive, we might instead see selection for those characteristics.
"If you don't have to worry about being eaten by a lion, if you don't have to worry about being killed by another tribe in battle or starving because you can't find enough tubers to eat, increasingly what dictates what DNA will survive and perpetuate and spread throughout the population it's going to be who can find a mate, and then beyond that, not just 'oh yeah, you look attractive from across the bar', but who can successfully raise kids."
Photo: 123RF
Does he think we could evolve as a species to live longer lifespans?
Longrich said that while scientists believed some deep sea worms could live for as much as a thousand years in lifespan, and some sharks and turtles were believed to live for a couple of hundred years, judging by the longevity of some whales it was likely the maximum lifespan possible for a mammal would probably be a couple of hundred years, he said: "I don't know a reason why it can't happen."
Many different species of humans are now known to have lived, such as Neanderthals and Homo erectus. Could different human species evolve in the future?
"The trick is you need to have some sort of isolation - in prehistoric times it was geographic isolation. People lived in different areas so they didn't easily interbreed, and species went in different ways."
Have humans done a good job of adapting to the modern world?
Longrich was emphatic: "Oh no.
"Natural selection can act pretty fast, but cultural evolution works far faster. So we have evolved, our brain sizes have changed, our immune systems have changed, as we started domesticating cows and sheep we developed the ability to digest milk ... we are adapting to this world, but there's this lag.
"Kids want to play with sticks because at heart they're still hunter gatherers who want to hunt with spears and bows, so we're not fully adapted to this world, and I think that's maybe the source of a lot of the ills of society - we've created this world but we're not really very well adapted to."
Photo: 123rf
Despite adapting very well in some ways, the ways we have not adapted well on cause us grief.
"I think what we've done a very good job of is, with our society it meets our physical needs very well - we live very long lives, the average life expectancy in a western country is close to 80 years.
"But as you see people with increasing rate of stress, anxiety, depression, it's not meeting our psychological needs well. That's because we adapted in these very small intimate social groups where everyone knew everyone else, we were surrounded by friends and family all the time.
"So I think that's the big disjunct, is civilisation has done an extraordinarily good job of providing for our material needs, but it's like Jesus said: "Man cannot live on bread alone" - we have these psychological needs.
"So one of two things has to change, either we're going to adapt, we're going to evolve our DNA changes to where we are psychologically well adapted to these institutions and cultures, or our cultures have to change to meet these needs, more like the hunter gatherer lifestyles that we used to live in."
Mexican painter José Clemente Orozco's mural of the ancient myth of Prometheus. Photo: Public Domain
This is where wider awareness of the journey through past, present and to the future helps, Longrich said.
"I think it's one of the big problems we face going forward, but it's kind of not a new problem - if you go back and look at ancient mythology, the earliest civilised peoples were profoundly sceptical about the benefits of civilisation - that's the myth of Prometheus ... or the Epic of Gilgamesh, when Gilgamesh's rival and friend Enkidu the wild man is civilised he's horrified by being brought into civilisation, or the myth of Eve and the Apple - knowledge of good and evil comes with all these prices. So Western civilisation is interestingly very sceptical about progress.
"It comes at a price. You don't get something for nothing. Which is not to say progress is bad, but you have to think carefully about what kind of societies do you want going forward.
"We kind of have a choice - either our societies keep going the way they're going and we're going to evolve slowly to meet them or we're going to engineer institutions to be the way we want."
But, we're better equipped now to direct the human race towards a better future, he said.
"I think that's the difference with historically how evolution worked - that we understand what's happening to ourselves now, we control both aspects of it - we control evolution of our physical bodies in terms of who we choose to mate with, our DNA, but we also control our cultural evolution, and there's this weird interplay between the two.
"So we know it's happening, we watch it happening, we see it happening at the genetic level and at the cultural level and we can kind of can steer it."
