The stomach, as most are aware, is the place food winds up after being eaten. Inside of it, along with food and bacterial biota are pepsins which help break down proteins, along with acids that soften food to make it easier to digest. Both pepsins and acids exist because of characteristics within our genome. Without them, we’d die. But not all vertebrates have stomachs or some other similar organ to serve as a vessel for the dispersal of pepsins and digestive acids. This got the researchers to wondering if the genes responsible for causing the creation of them might have gone away as well. To find out, they studied 14 species of animals both with and without stomachs to see what differences they might have. More specifically, they checked to see if there were any differences in their genes.
Read more at: Phys.org