A cookbook is handed down through generations, but one day a borscht recipe suddenly picks up a secret ingredient from a pastry chef. After that, the taste recalls not just ancestors but also a neighborly trick. In the standard model of evolution, genes behave the same way. Genes are instructions for the organism. Some are lost by chance, others transfer directly between unrelated species. Bacteria swap antibiotic resistance genes like chefs swap recipes. But even our genome is 8% viral fragments, bequeathed by primate ancestors. A new mathematical model found: when transfers occur at a steady rate, telling them apart from random losses using only gene trees is nearly impossible. The fingerprints of both processes are too alike. The evolutionary tree resembles a cookbook full of borrowings.
Horizontal gene transfer in bacteria is sometimes compared to 'file sharing' on the internet: it allows useful genes to spread instantly.
In science fiction, the idea of gene swapping between species is played out in 'Jurassic Park,' where dinosaurs were given frog DNA.