The genomes of 51 giraffes were studied:
Since humans started classifying species, the iconic giraffe, which roams the savannahs of Africa munching on trees and towering above all other animals, had been considered a single species. With the advent of genetic sequencing, suggestions of six, eight, four and three species of giraffe, with varying numbers of subspecies, have been proposed.
And the debate has been “surprisingly heated,” says Heller. “It’s a problem of life being messy and difficult to pigeonhole, and humans having brains that compulsively put things into pigeonholes,” adds wildlife biologist Derek Lee of Penn State University who did not participate in the study.Ruth Williams, “Whole-Genome Data Point to Four Species of Giraffe” at The Scientist (May 6, 2021)
And the matter is far from settled. Meanwhile, the giraffe genome will prove a headache for the Darwin Beats Lamarck Punch and Judy Show.
Most summaries of the [giraffe genome] paper, including those in Science magazine and The Scientist, fail to account for the long neck — the very trait that most interested the early evolutionists. Instead, they focus on one particular gene named FGFRL1. In humans and mice, this gene is associated with bone strength and with blood pressure.
The team decided to check what happens when the giraffe version of the gene, with has seven differences from the gene in other mammals, is inserted into mouse embryos. The mice did not grow long necks, but they grew more compact and denser bones. Most importantly, they also survived a drug that raises blood pressure. Giraffe blood pressure is twice that of humans. It appears, therefore, that giraffes have a version of FGFRL1 that protects them from the expected damage to tissues and organs from blood pressure high enough to pump blood up to their lofty 5-meter-high heads. Why is this gene also associated with bone growth?
A few other interesting things were found in the genome: genes related to circadian rhythms that might explain why giraffes get by with little sleep (since getting up off the ground is a “lengthy and awkward procedure”), why their olfactory genes are reduced (“probably related to a radically diluted presence of scents at 5m compared to ground level”), and why their eyesight is so sharp (assumed to be an evolutionary trade-off for less reliance on the sense of smell). The most obvious traits of the giraffe — the long neck, long legs, fur patterns and all — have not been addressed in the paper. The authors admit that “more research on the functional consequences of giraffe-specific genetic variants is needed.”Evolution News, “Giraffe Genome Is Not Evolutionary” at Evolution News and Science Today (May 7, 2021)
Well, wait. If a big survey of the giraffe genome can’t tell us the answers to the most puzzling questions about one of the most remarkable animals, where should we look for answers next?