Washington: Researchers at Stanford University have identified a change in gene expression between humans and primates that may have helped give us an edge to walk upright.
Astonishingly, the team discovered the gene expression by studying a tiny fish called the threespine stickleback that has evolved radically different skeletal structures to match environments around the world.
"It is clear that tweaking the gene can result in significant changes not just in the skeletal armor of the stickleback but also in the hind-limb development of humans and primates," explained David Kingsley, professor of developmental biology at Stanford.
“This change is likely part of the reason why we have evolved from having a grasping hind foot like a chimp to a weight-bearing structure that allows us to walk on two legs,” he noticed.
Along with researchers from HudsonAlpha Institute for Biotechnology in Huntsville, Alabama, the Stanford team identified the area of the genome responsible for controlling armour plate size.
They then looked for differences there in 11 pairs of marine and freshwater fish with varying armour-plate sizes.
They homed in on a region that includes the gene for a bone morphogenetic protein family member called GDF6.
Due to changes in the regulatory DNA sequence near this gene, freshwater sticklebacks express higher levels of GDF6, while their saltwater cousins express less.
Kingsley and his colleagues wondered whether changes in GDF6 expression levels might also have contributed to critical skeletal modifications during human evolution.
In previous surveys, they found over 500 places in which humans have lost regulatory regions that are conserved from chimps and many other mammals.
Two of these occur near the GDF6 gene. They homed in on one in particular.
“These bone morphogenetic proteins are strong signals for bone and cartilage growth in all types of animals," added Kingsley in a paper published in the journal Cell.