“If we were to weigh all the ants in the world, they would weigh as much as all humans,” presenter Chris Packham said in a recent BBC documentary. Can it be true?
This was maintained for the first time by Professor Edward O. Wilson, from Harvard University (United States), and the German biologist Bert Hoelldobler in their 1994 book “Journey to the ants”.
The estimate is based on an earlier calculation by British entomologist CB Williams, who put the number of insects alive on earth at any given time at one million trillion.
“If, to take a conservative number, one percent of that is ants, the total population would be 10,000 trillion,” Wilson and Hoelldobler wrote.
“A worker ant can weigh between one and five milligrams on average, depending on the species. Combined, all ants together weigh as much as all humans together.”
Wilson and Hoelldobler’s idea is based on the idea that the average human weighs a million times more than the average ant.
And how long does this argument hold up to close examination?
An average human weighs 62 kilos, so that would mean that ants weigh about 60 milligrams.
“There are ants that weigh 60 milligrams, but they are very large,” says Francis Ratnieks, a beekeeping professor at the University of Sussex, UK.
“The common ant should be around a milligram or two.”
With some 13,000 species in the world, the difference in size goes from those that measure one millimeter to those of 30.
So it’s likely that weight will certainly vary as well: although many experts seem to agree that the average weighs 10mg.
Of course, nobody knows that there are ants in the world. The BBC documentary says it’s not ten million trillion but a hundred trillion, and still talks about them weighing as much as humans.
Experts from the ant laboratory at Bristol University’s Natural History Museum and the Bee, Wasp and Ant Recording Society (BWARS), among others, say this is not a realistic estimate.
Even with Wilson’s and Hoelldobler’s numbers, their calculation is wrong. The 7,200 million human beings weigh about 450,000 million kilos.
If we consider that there are ten million trillion ants in the world with an average weight of 4 milligrams, the weight comes to be 40,000 million kilos.
Even if we take the population at the time they wrote the book and a slightly lower median weight, they’re still a long way off.
But Ratnieks believes that Wilson and Hoelldobler’s sustainability, while not true relative to the current population, may have become accurate at some point.
“I think if we go back 2,000 years, it is true that they could have weighed more than humans,” he says.
“But we must remember that humans are getting fatter. We are not only growing in population but in weight, so I think we left the ants behind a long time ago.”