It was sad enough that a lowland gorilla was killed a few days ago out of safety concerns for a toddler that fell into his enclosure at the Cincinnati Zoo. But leave it to the original Make America Hate Again shock jock to pile on, mangle evolutionary biology, and shortchange gorillas in the process.
On his Tuesday radio show, the conservative host opined that PETA activists opposing the capture of animals had “obviously has not read Genesis.” … “A lot of people think that all of us used to be apes,” Limbaugh added. “Don’t doubt me on this. A lot of people think that all of us used to be gorillas.”
It’s not clear who those people are, but if they think anatomically modern humans evolved from modern gorillas, they are deeply mistaken. We know that modern humans evolved from earlier versions of now extinct hominids. The precise line of descent gets hazier with time, but dozens of transitional fossils found in the exact temporal progression leave no doubt about it, and more recent molecular analysis of genetic material might as well be a YouTube video of evolution firing the smoking gun.
There are many forks in that long evolutionary road between various ancestors of modern primates and our own. It reaches way back into one of the most fascinating times in the remote past. If someone can’t or won’t appreciate that rich, biological legacy, it really is their loss.
Asking why gorillas didn’t evolve into humans makes as much sense as asking why humans never evolved into gorillas. But the evolutionary origin of gorillas is far less clear than it is for humans. Gorillas, along with chimps, gibbons, and orangutans spend much of their lives in or near tropical rain forests. Because of scavenger density and surface conditions in those places, fossil remains from possible ancestors of these great apes are few and far between. For the same reason, the fossil trail of human ancestors leads right up the edge of those forgotten jungles and all but disappears. But genetic analysis shows that the ancestors of gorillas split off from the common ancestor of humans and chimps about 7 million years ago, and went on to evolve into the several extant species we see today.
That date neatly coincides with the end of the Miocene, a fascinating geological epoch which could be called the age of the apes. This was a wetter world marked by enormous rain forests virtually spanning entire continents, in which apes flourished and diversified for millions of years. It is estimated that more than 100 distinct species existed over the course of the Miocene, from Gigantopithecus at 10 feet tall and weighing half a ton, to an adorable miniature version that barely topped 10 pounds. Given more time, it’s possible that apes would have radiated into other, surprising eco-niches, but about then nature dealt them some lousy hands.
The Miocene, like so many ancient worlds, was doomed. Far to the south, Antarctica had already separated. It was soon thermally isolated. Snow fell and the ice-sheets thickened, gradually locking up more and more water, reflecting more and more sunlight, until the whole world slowly cooled and dried out. The great rain forests finally broke up, giving way to expanding grasslands and desert, impossible barriers for the purely arboreal apes to cross.
The warm old world inexorably shifted toward the cooler, drier Pliocene and Pleistocene, and the first of what would be many glaciers began to quicken and flow south, freed at last from their icy Arctic sanctuaries. Most of the apes went extinct as the Miocene drew to a close. Some, like the ancestors of modern gorillas, retreated into the scattered remains of tropical forests still carpeting the equatorial lowlands and hugging the sides of gentle African mountains. Others managed to eke out a living in between the plains and the forests.
But new species took hold. The new grasslands exploded with massive numbers of ice age megafauna, including some of the largest herds and heaviest land mammals to ever roam the planet. Our picture of what happened in the oceans is not as clear, as the fossil record there is sparse. But cooler water holds more oxygen than warmer water. The shelves of ice extending into the sea around both poles would have grown, and nowadays that icy edge is about as seasonally rich with life including krill, crab, fish, birds, whales, and all kinds of pinnipeds (seals and walruses) as the cryosphere can be.
And those few surviving species of ape? At least one of them developed bipedal locomotion, a singular novelty that would enable the new walkers to colonize that growing African savanna, where they would first learn to gather and scavenge then actively pursue larger and larger prey and, more recently, evolve into us.
The Age of the Great Apes has come and gone, but without Them there would be no Us: Not a single musical note would have ever been scored, not one brush stroke in one painting ever rendered, no word ever written. There would be no Hubble, no Pillars of Creation or distant misty spiral galaxies adorning a billion flat screens. We have our faults, but without us, not one living thing on Earth could truly admire the breadth of nature’s many symphonies that led to all the magnificent cosmic beauty above and biological treasures below. We are all enriched by these ancient sights and sounds, carefully reconstructed by science from once living stone, frozen in DNA or carried across oceans of time and space by visible and invisible light. We too often take them for granted, or foolishly dismiss them.
Speaking of which—how sad for Rush Limbaugh. It’s merely an individual pity that he willingly denies himself any appreciation of that rich, natural history. But let’s reserve our greatest sympathy for the millions of listeners he so eagerly swindles into wallowing in that same shallow pit of willful ignorance, right along with him.