From The Scientist: Genome Reveals Clues to Giraffes’ “Blatantly Strange” Body Shape

An updated giraffe genome, published March 17, 2021 in Science Advances, reveals new insights into how the species accommodates a “blatantly strange body architecture.” 

Author, Amanda Heidt writes…

With their long necks, giraffes are a poster child for evolutionary oddities, but scientists know very little about the genetic underpinnings of such an extreme adaptation. An updated giraffe genome, published March 17 in Science Advances, reveals new insights into how the species accommodates what Rasmus Heller, an evolutionary geneticist at the University of Copenhagen and an author on the new study, calls a “blatantly strange body architecture.” Giraffe’s bones grow faster than any other animal, for instance, and the blood pressure required to pump blood up its six-foot neck would be fatal to humans.

Unlocking giraffeness 

When the team probed the genome further, they identified almost 500 genes that are either unique to giraffes or contain variants found only in giraffes. 

A functional analysis of these genes showed that they are most often associated with growth and development, nervous and visual systems, circadian rhythms, and blood pressure regulation, all areas in which the giraffe differs from other ruminants. As a consequence of their tall stature, for example, giraffes must maintain a blood pressure that is roughly 2.5 times higher than that of humans in order to pump blood up to their brain. In addition, giraffes have sharp eyesight for scanning the horizon, and because their strange bodies make it difficult for them to stand quickly, they sleep lightly, often standing up and for only minutes at a time, likely a result of changes during evolution to genes that regulate circadian rhythms.

Within those hundreds of genes, FGFRL1 stood out. In addition to being the giraffe’s most divergent gene from other ruminants’, its seven amino acid substitutions are unique to giraffes. In humans, this gene appears to be involved in cardiovascular development and bone growth, leading the researchers to hypothesize that it might also play a role in the giraffe’s unique adaptations to a highly vertical life. 

The Scientist

Note that seven amino acid substitutions needed to form a unique, functional gene is highly unlikely to occur naturally. Consider the following quote from Michael Behe:

Any particular adaptive biochemical feature requiring the same mutational complexity as that needed for chloroquine resistance in malaria is forbiddingly unlikely to have arisen by Darwinian processes and fixed in the population of any class of large animals (such as, say, mammals), because of the much lower population sizes and longer generation times compared to that of malaria…. (By “the same mutational complexity” I mean requiring 2-3 point mutations [amino acid substitutions]…)

Evolution News–Behe

Repeatedly, further research in a given field tends to reveal greater evidence for intelligent design, not less.

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