Recently, the OneZoom website, run by James Rosindell and Luke Harmon at Imperial College London, released an illustration of the ancestral tree of all tetrapods–that is, all birds, reptiles, mammals, and amphibians. Previously, the group had produced trees for birds, mammals, and amphibians alone, but now all three have been combined with the various groups of reptiles filled in as well. In the immediate future, the group is planning on adding fish and plants with the ultimate goal being an illustration of the ancestral relationships of all extant life on Earth.
Here’s the launch video the group released at the same time that the mammalian tree became available:
If you spend some time playing around with it, you can find out quite a few surprising relationships. For instance, as the tree above shows, crocodiles are more closely related to birds than they are to turtles or lizards.
As an example of how to navigate through the tree, here’s how to find humans. First, humans are mammals, so, zoom in on the mammalian branch, which as you can see, splits into three clusters: Monotremes (egg-laying mammals), Marsupials (mammals that give birth to live young but have no placenta), and Placental mammals.
Zooming in on the Placental mammals, we can see the major subdivisions, though many of those groups are not very intuitive. “Elephants, Elephant shrews, and more” incudes aardvarks and sea cows, while “Carnivorans, Bats, Hedgehogs, and more” includes shrews, all hoofed mammals, and whales. The fact that three of these groups contain animals with “shrew” as part of their name is a hint as to what our Cretaceous period ancestors looked like. Of course, since humans are primates, “Primates, Flying Lemurs, and Treeshrews” is the category we’re looking for.
Here wee see that the lemurs are considered primates but flying lemurs are not and that old world monkeys are more closely related to us than they are to new world monkeys. At this point it’s pretty obvious where to go.
Among the apes, most species are gibbons, rather than our closer, more charismatic relatives, the great apes. However, it is worth noting at this point that the color-coding of this tree is such that brown means a species is endangered, red means that it is critically endangered, black means the conservation status has not been evaluated, while the light green color means that there is the least concern regarding the conservation of the species. With that in mind, it is pretty clear which leaf represents humanity.
That we are the only non-endangered member of the great ape family speaks to the unique nature of our success. While each of them are uncommonly intelligent and social, they fall into rather narrow niches and are confined to equatorial jungles as their habitat, while we’ve managed to spread around the globe remaking the world in our own image. As of now, we stand as the only species that’s developed the means to leave the planet and the species with the most capability for destruction of any in the entire tree of life. What a difference 8.8 million years makes.
That’s the power of the OneZoom layout, showing relationships between ancestral groups of animals from tetrapods as a whole all the way down to humans. I highly recommend taking some time to explore the ins and outs of the tetrapod tree. There’s a great deal to learn about the relationships between land-dwelling vertebrates, and humanity is only the beginning.