Domestic animals’ cuteness and humans’ relatively flat faces may be the work of a gene that controls some important developmental cells, a study of lab-grown human cells suggests.
Some scientists are touting the finding as the first real genetic evidence for two theories about domestication. One of those ideas is that humans domesticated themselves over many generations, by weeding out hotheads in favor of the friendly and cooperative (SN: 7/6/17). As people supposedly selected among themselves for tameness traits, other genetic changes occurred that resulted in humans, like other domesticated animals, having a different appearance than their predecessors. Human faces are smaller, flatter and have less prominent brow ridges than Neandertal faces did, for instance.
Both of those big domestication ideas have been just that, with not much hard evidence for or against either. Some studies have suggested that differences in some genes implicated in neural crest cell function might have been important in the domestication of cats (SN: 11/10/14), horses (SN: 4/27/17) and other animals (SN: 5/11/15). But none of those studies explained how those genetic differences led to altered behaviors or looks between wild and domesticated critters.
In the new study, researchers studied cells from people with developmental disorders to learn what makes neural crest cells tick. One gene, BAZ1B, is a neural crest cell boss, the team found, controlling 40 percent of genes active in those cells. Altering levels of BAZ1B’s protein affects how quickly neural crest cells move in lab tests, the scientists report December 4 in Science Advances.
Genes under BAZ1B’s direction are among those that changed both in animals during domestication and in modern humans as they evolved, the researchers also found. Some variants of those genes are found in nearly every modern human, but either weren’t found or were not as prevalent in the DNA of their extinct Neandertal or Denisovan cousins (SN: 9/19/19), the team says.
Then in 2014, three scientists proposed that as people selected animals for tameness, they also happened to select for genetic changes that slightly hamper movement of some developmentally important cells (SN: 7/14/14). These neural crest cells are present early in embryonic development and migrate to different parts of the embryo where they give rise to many tissues, including bones and cartilage in the face, smooth muscles, adrenal glands, pigment cells and parts of the nervous system. The researchers’ idea was that mild genetic changes might produce neural crest cells that don’t move as well, leading to domestic animals’ cuddlier look.
Domestic animals’ cuteness and humans’ relatively flat faces may be the work of a gene that controls some important developmental cells, a study of lab-grown human cells suggests.
Some scientists are touting the finding as the first real genetic evidence for two theories about domestication. One of those ideas is that humans domesticated themselves over many generations, by weeding out hotheads in favor of the friendly and cooperative (SN: 7/6/17). As people supposedly selected among themselves for tameness traits, other genetic changes occurred that resulted in humans, like other domesticated animals, having a different appearance than their predecessors. Human faces are smaller, flatter and have less prominent brow ridges than Neandertal faces did, for instance.
Domesticated animals look different from their wild counterparts as well. Shorter snouts, curly tails, floppy ears and spotted coats are all traits that tend to pop up in domesticated animals. But until recently, no one had an explanation for this “domestication syndrome.”
Then in 2014, three scientists proposed that as people selected animals for tameness, they also happened to select for genetic changes that slightly hamper movement of some developmentally important cells (SN: 7/14/14). These neural crest cells are present early in embryonic development and migrate to different parts of the embryo where they give rise to many tissues, including bones and cartilage in the face, smooth muscles, adrenal glands, pigment cells and parts of the nervous system. The researchers’ idea was that mild genetic changes might produce neural crest cells that don’t move as well, leading to domestic animals’ cuddlier look.
