• Question: Is it possible to trace back every single evolution before mankind?

    Asked by daniel3xmas18 to Tomas, James, Anthony on 9 Jan 2019. This question was also asked by lectureattendees.
    • Photo: Anthony Redmond

      Anthony Redmond answered on 9 Jan 2019:

      In theory, if we had complete DNA sequences of every species or individual who ever lived, as well as a clear idea of what they looked like from a complete and accurately dated fossil(or live/preserved specimen), then it would be possible to get very close to this.
      But, it would probably be computationally impossible, at least with our current hardware!
      And in reality we will never have the DNA or fossils of every species that ever lived, because DNA and soft-bodied animals are easily broken down, especially over vast evolutionary timeframes, such as millions or even more than a billion years. For example, the DNA and fossils of a worm species that lived in the ocean around 300 million years ago, and survived as part of a small population for 50,000 years, before becoming extinct, are almost certainly lost forever.

      Its not all bad news though, we are often most interested in evolutionary events that have made us who we are, or in uncovering the evolution of the uniqueness of other species that exist today. Luckily there are still many useful fossils that have been discovered to help us understand our evolution (e.g. fossils of species that are a half way between fish and land vertebrates, showing fins changing to limbs, or those of other human species, such as neanderthals). We can also use the DNA of other existing animals to better understand when important genetic changes happened in our history. By comparing the DNA and genes of lots of species, as well as considering fossils of their extinct relatives, we can work out how species are related to each other, and map how and when important genetic changes happened in the past. Doing things this way can also allow us to work out the biology of our ancestors, because we get a glimpse of what genes they had, and how they might have worked. In some of my own work I have done this to help figure out what kind of immune systems our early animal ancestors had hundreds of millions of years ago.


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