Researchers combing the Red Sea have identified a new species of clam, a giant one that could measure more than a foot in length and may have been one of our ancestors’ favorite meals. The oversized mollusk went undiscovered for so long because it accounts for only one percent of the current population of clams. However, checking the fossil record, the scientists found that the giant clam once made up 80 percent of the population, then dropped off precipitously around 125,000 years ago, a date that roughly coincides with early humans coming out of Africa.
And those hunter-gatherers, the study says, probably couldn’t resist a seafood meal that not only offered no resistance but also preferred shallow coastal waters, meaning they were just sitting there waiting to be snatched up. Some scientists think easy-to-get food supplies were one of the main reasons early humans would have left Africa—and not much is easier to get than a giant clam in shallow water.
The decline and near-extinction of the giant clam, however, is another example of our ancestors using their newfound intelligence to wreak havoc on their environment. Megafauna were especially vulnerable to humans because they had nowhere to hide, and the giant clams were an even easier target since they had no chance of running away. Their demise, the researchers say, might be the first ever example of ocean over-harvesting, which is one of the biggest environmental disasters today: Three quarters of known fish species are being hunted at or beyond a sustainable level.
So it looks like over-fishing is nothing new—we may have been doing it for more than 100,000 years.