The idea of humans growing tails, chicken growing teeth and snakes growing legs may not be as far fetched as we think.
New research led by Flinders University has found that reverse evolution - where organs or features lost millions years ago are redeveloped - is possible under certain conditions.
It pointed to how some of Australia's largest kangaroos have changed the structure of their teeth to resemble those of their ancestors in response to their changing diet.
As forests retreated towards the coastline over millions of years, kangaroos were forced to eat more grass, with their teeth needing to cut rather than chomp away at their food, the researchers say.
That led to the shape of their molars changing to more closely resemble those of their more distant ancestors.
"We show that small changes to a 'rule' that determines how teeth form in the embryo have allowed some kangaroos to partly turn back the clock on evolution," PhD candidate Aidan Couzens said.
"Using these rules, we can start to predict the pathways evolution can take."
"We found that features lost in evolution can re-evolve when evolution tinkers with the way features are assembled in the embryo."
The research, published in the journal Evolution, casts some doubt on the widely held view that once a structure or organ is lost during the course of evolution, it can't be recovered.
Co-author Gavin Prideaux said biologists had often discounted the potential for evolution to shift into reverse.
But he said the latest research argued that reanimating genetically mothballed features might be allowed by evolution under certain circumstances.
