The tree of life doesn’t actually look like a tree. It looks like a galaxy spiraling out from the beginning of the Earth.
That at least is how it appears in a new evolutionary timeline. It’s based on research that documents the development of more than 50,000 species, from the earliest eukaryotes to recent chimpanzees. The design points to the finding that evolution–the creation and diversification of new species–is constant, not episodic, as previously argued.
“The constant rate of diversification we found indicates that ecological niches of life are not being filled up and saturated,” says Blair Hedges, a professor at Penn State. “[It] shows that speciation is more clocklike than people have thought.”
The research, published in the journal Molecular Biology and Evolution, is based on data from 2,274 previous studies. It used computer algorithms to understand DNA mutations to see how species diverged from one another. For example, it shows that dogs and humans had common heritage 94 million years ago (which makes sense given the closeness of humans and dogs).
The work is part of the Timetree of Life initiative (TTOL), which has a nifty web site here that lets you look up when species separated from each other.
“The ultimate goal of the TTOL is to chart the timescale of life–to discover when each species and all their ancestors originated, all the way back to the origin of life some four billion years ago,” Hedges says in a press release.