LONDON, Jan. 3, 2020 – US scientists have made a prediction that some yet-to-evolve intelligent species a hundred million years into the future can test. One day the fossil record will be more than usually rich in the complete skeletons of a small number of creatures: pigs, sheep, cattle and humans, many of the last arranged seemingly in ranks.

The assemblage from what many scientists now call the Anthropocene – the geological era dominated by Homo sapiens – will be entirely unlike the pattern of preserved relics from all the other geological eras in the last 500 million years.

“Fossil mammals occur in caves, ancient lake beds and river channels, and are usually only teeth and isolated bones,” said Roy Plotnick, a palaeontologist at the University of Illinois in Chicago. “Animals that die on farms or in mass death due to disease often end up as complete corpses in trenches and landfills, far from water.”

Also available for study will be a vast array of undisturbed examples of one species that already far outnumbers all other large wild mammals. “In the far future, the fossil record of today will have a huge number of complete hominid skeletons, all lined up in rows.”

The thesis, outlined in the journal The Anthropocene, is a simple one. The evidence of past life preserved in the rocks is the only key to the story of life on Earth, and it has unfolded until now entirely by caprice.

A lower jaw, the oldest known fossil of the genus Homo. Image: By Gerbil, via Wikimedia Commons

“The future mammal record will be mostly cows, sheep, goats, pigs, dogs, cats and people themselves”

Animals that died in the Triassic, Jurassic or the Cretaceous were incompletely preserved. Upon death, they were liable to be dismantled by scavengers, swept away by floods, incinerated by fires, buried by lava or demolished entirely by microbes. Preservation of any kind was entirely a matter of geological caprice and bone structure: soft-bodied animals – and most living things have always been boneless – have almost no chance of preservation.

The North American passenger pigeon astonished the first European settlers. It existed by the billion-fold: one flock could be a mile wide and 200 miles long.

The last survivor perished in 1914 and, says Steve Jones in 1999, in his much-recommended examination of evolutionary insight, Almost Like a Whale, without a written record, no-one would now know it had ever existed: no fossil has ever been found.

The argument by Professor Plotnick and a colleague is a simple one. If preservation in fossilised form is a lottery, humankind has now taken over the management and rigged the odds.

Humans evolved from primate ancestors, but no primate species ever flourished in such numbers. Global population has soared almost eightfold in the last two centuries, and with humans the population of domesticated animals has multiplied dramatically: one species now threatens to eliminate many of the other inhabitants of the planet.

Preservation more probable

The mass of humanity, according to one calculation, long ago began to outweigh the gross mass of all other wild mammals on the planet, by at least 10-fold. And in such numbers, humans and their chosen species should stand a much better chance of preservation far into the future.

Homo sapiens has already fashioned cities, industries and constructions that gross up to trillions of tonnes of cement and metal, and in a few decades laid down a stratum of seemingly indestructible polymer material in the form of plastic cups, bottles, nets, cables and containers.

Erosion, earthquakes and time alone may wipe away many of the scars left by most construction work, but some will survive as evidence that at least one intelligent civilisation made it through evolution’s obstacle race before possibly ensuring its own collapse.

The chances of long-term preservation of the bones of the blue whale, the African lion, the mountain gorilla, the emperor penguin or even the jungle fowl, ancestor of the broiler chicken, will remain vanishingly small. But the factory farms and orderly cemeteries of today will dominate the evidence.

“The chance of a wild animal becoming part of the fossil record has become very small,” said Professor Plotnick. “Instead the future mammal record will be mostly cows, sheep, goats, pigs, dogs, cats and people themselves.” –

Tim Radford, a founding editor of Climate News Network, worked for The Guardian for 32 years, for most of that time as science editor. He has been covering climate change since 1988.