A pair of researchers has pieced together the genome of the ancestor of all animals, the New York Times reports.
Jordi Paps from the University of Essex and Peter Holland from the University of Oxford first drew a phylogenetic tree of animals and selected 62 species from across the tree to study in depth, the Times says. They then analyzed similarities and differences within those species' protein-coding genes
Through that — as Paps and Holland report in Nature Communications — the pair identified 6,331 genes that were present in the ancestor of all metazoans, which lived 650 million years ago. Further, they note that this ancestral metazoan genome contained 1,189 novel genes. These genes, the Times notes, must've evolved in proto-animals. Paps tells the Times that these new genes may have appeared because something in the environment promoted mutations, though, the genes may have also arise more slowly over time. But as Quartz points out, researchers have no idea what this ancient animal looked like.
The researchers also note that, of the genes in the human genome, about 55 percent were already present in this ancient metazoan ancestor, the Times adds. "The big surprise was how many of them there were," Paps says.