Experts calculated how our physical appearance could possibly change under a number of scenarios, including a ‘water world’ if melting ice caps cause sea levels to rise drastically.
They also considered what would happen in a second ice age which could be triggered by something like an asteroid strike, and if humans colonized other planets.
Dr Matthew Skinner, a paleoanthropologist at the University of Kent, examined the three scenarios, working with artist Quentin Devine to help visualise how humans could look in the future.
Dr Skinner said some changes – such as webbed feet and hands becoming widespread – could very well take place quickly as some humans already have a genetic mutation that produces webbing.
Other changes to allow humans to live in extreme conditions may only take place over hundreds of generations of natural selection, or require genetic engineering.
He said: ‘We could genetically engineer ourselves if important enough to survive. Some of these things we might try to develop as a necessity rather than occurring over time naturally. Others could occur over tens of thousands of years.’
To adapt to a ‘water world’, Dr Skinner expects humans could very well develop webbed hands and eyes like those of cats to help us see in the poor lighting conditions underwater.
We would also retain a layer of baby fat into adulthood as an insulator for spending long periods of time submerged.
Regular foraging in shallow waters could lead us to develop artificial ‘gills’ which would help us breathe, extracting oxygen from the water and delivering it to the bloodstream.
This would also lead to our lung capacity becoming sadly reduced, and our rib cages shrinking.
An additional layer in the retina – like cat’s eyes – could develop to help us see in poor light when we are under water. We might also evolve an extra translucent eyelid to protect our eyes from water.
In the scenario of an ice age, Dr Skinner predicts that our skin would become quite pale to help us produce more vitamin D from less sunlight, we would have more body hair, and we would develop more muscular type physiques.
Our noses and face size would increase to help warm inhaled cold air in the nasopharynx, which is the area behind the nose.
We would become stronger, as reduced resources and technologies would mean physical power becomes more and more important.
This would be particularly true for men, who would need to attract a mate through their physique rather than intellect, much like gorillas in the natural world do.
Females would also need to become physically stronger. Body hair would need to increase as serve as a means of insulation.
And if we were to colonize other worlds, the body would need to undergo a variety of changes to adapt to much lower levels of gravity.
These could include longer arms and shorter legs as in low gravity walking may be less necessary. Upper and lower limbs would become more important and become similar in length, as seen in orangutans, who prefer to swing through trees rather than walk.
We could develop ‘opposable’ big toes as our feet become more useful for holding onto things in low gravity.
Dr Skinner said eventually there could be a complete loss of human teeth and a reduction in jaw and mouth size down to something you can just fit a straw into, which would result in our faces becoming smaller.
The overall effect would be to make us look more like newborn babies, whose mouths are only needed to swallow.
Having a lack of natural predators, humans’ overall body size would be reduced. This is seen in nature in a phenomenon called ‘island dwarfing’, where mammals have low resources available but also few predators.
Dr Skinner produced his predictions just as the new series of science fiction drama Extant is launched on the Syfy Channel this week.