Take a look at the tree of life below. It illustrates our connection to the other living beings on this planet from one common ancestor, that would be in the ‘Earth Birth’ circle of the image below. If you click on the image to see it full size, you’ll find us humans on the left side, at the bottom.
© Leonard Eisenberg, 2008, 2017
I want to make two points here:
1 We and all other living beings have the same common ancestor: we’re all related.
Isn’t it amazing to think about how, if we go back in time long enough, we’ll find a common ancestor for us, humans, and a rose? According to the estimation of the website evogeneao [1], we branched off that ancestor around 1.6 billion years ago!
© Leonard Eisenberg, 2008, 2017
As we get closer together on the tree, we also have more similarities, even in behavior. For example, we can be impressed by how a chimpanzee mourns the death of his mother and first is in denial and ends up dying of grief [2]. However, we shouldn’t be so surprised, since we share much of the brain functions that lead to similar behaviors. Needless to say, the chimpanzee is much closer related to us than the rose.
2 To reach the body we have today, we’ve gone through millions of years of tiny changes.
Over millions of years, all creatures on Earth have evolved from one common ancestor to the way they are today. These adaptations happened extremely slowly. If a species had traits that were a disadvantage in a certain environment, it most likely died out. Other changes caused animals to have traits that ensured their survival. That’s natural selection [3].
These changes weren’t following a blueprint and going in one constant direction: something that had happened and granted an animal an advantage, later could become a disadvantage due to environmental changes. As the French biologist and Nobel laureate François Jacob said, the action of natural selection isn’t like an engineer, but like a tinkerer:
“Natural selection has no analogy with any aspect of human behavior. However, if one wanted to play with a comparison, one would have to say that natural selection does not work as an engineer works. (…) it works like a tinkerer who uses everything at his disposal to produce some kind of workable object.”
François Jacob, Evolution and Tinkering (Science, Vol. 196, 1977)
Evolution can be messy!
| For more information |
| 1. evogeneao.com Great depiction of a tree of life showing the ramifications of life over millions of years. As the website states, the intention is to depict how “we are related not only to every living thing, but also to everything that has ever lived on Earth.” and the tool has some distortions to make it easy to understand. Check the website for further clarification. |
| 2. Article ‘Grief, Mourning, and Broken Hearted Animals’, by Marc Bekoff, Ph.D. Article about the fact that animals also grieve when losing family and friends |
| 3. Video “Evolution and natural selection”, Khan Academy Short video explaining natural selection in a simple way |
Edited: inserted the images of evogeneao’s Tree of Life and made minor adjustments to the text.