The story of mammals started in the deep past, more than 250 million years ago. But for much of that history, they were but a footnote, underdogs living in a world of giants – most notably dinosaurs. But in the wake of the asteroid impact 66 million years ago, the mammals, thanks in part to their small size, survived.
Having inherited the world from the dinosaurs, they went on to claim it as their own. Mammals’ unique attributes of being warm blooded, giving birth to live young and feeding those young with milk meant they had the potential to achieve global domination. But getting there wasn’t easy, as Earth underwent a period of intense cooling. While plunging temperatures doomed species like giant Megacerops, and the evolution of a new type of plant, grass, led to the thriving of other mammals like Doedicurus.
Whatever obstacle was thrown their way, mammals – thanks to their adaptability and brainpower – were never held back for long. Eventually they would come to dominate the land, sea and air, having gone from measly underdogs to bigger than the biggest dinosaurs. But 2.5 million years ago brought them their greatest challenge yet: an ice age. From these frozen wastes would rise a new mammal, the most dangerous animal in the history of life on Earth: us.
Key moments
Megacerops – As the mammal dynasty’s roots date back 250 million years, Megacerops, a superb looking beast that used to roam what is now North America, was chosen to show the range of mammal appearances in the Paleogene (post-asteroid) period. The shrubby moorland / birch forest of the UK, though chosen in part due to COVID restrictions, was in fact a botanically accurate setting.
Grass – The arrival of grass, which really only spread across the planet around 30 million years ago but now covers 20% of the land surface, is one of the classic “who knew?” parts of the story of Life on Our Planet. Many people may assume grass has always been around, but in terms of the story of life, it’s a newcomer. The way it has shaped life on those great plains has been extraordinary, and ultimately, only two groups of animals have really adapted to it: insects, and as this chapter celebrates, mammals.
From the filmmakers’ point of view, the moment grass arrived in the story, their jobs became much easier. Removing grass from scenes that pre-date this was a nightmare, often involving a team of six people using tweezers to remove every blade!
Smilodon vs. Doedicurus – No animal illustrates the evolutionary arms race kicked off between predators and prey better than the giant, VW Beetle-sized armadillo-like creature, Doedicurus. Seeking a light-hearted sequence to juxtapose against the cheetah hunt, the filmmakers set up the concept of a juvenile Smilodon meeting Doedicurus but not quite knowing what to do. Here they leaned on decades of experience of filming big cats and seeing the nuances in their behaviour, including cheetahs seeking high vantage points, and lions testing out prey they haven’t met before, such as porcupines.
For sharp-eyed paleo experts watching at home, it’s worth pointing out that this Smilodon is different from the one portrayed in Chapter 1 (Smilodon fatalis). This is a juvenile Smilodon populator.
Snow Leopards – Occasionally the natural world throws a most unexpected curveball, upsetting the team’s careful plans. The tragic and fatal fall of the snow leopard from a huge cliff was perhaps the most extreme version of this. The moment the snow leopard leaps off the cliff was captured on one filming day. The camera operator hiked into position, spotted the leopard, framed the shot, started recording – and five seconds later, it was over.
Humpback Heat Run – This remarkable behavior shown by humpbacks was identified early as a filming priority. Because this had been captured for previous productions, the team knew they had to raise the bar. This involved inventing an entirely new system that would let them speed alongside the whales while also having a rock-solid underwater camera mounted to the boat. All of this was carried out off the waters of Hawaii, in association with the scientists of NOAA, to make sure that no whales were intimidated in any way during the course of filming.
Humans are Coming – The end of the mammals chapter teases the arrival of “the most dangerous” mammal: Humans, briefly glimpsed through the snows of the Ice Age. The sequence was filmed in wintry moors in North England on a cold January day. After a heavy snow, the producer, VFX supervisor and his partner borrowed a farmer’s old Land Rover to get up to the moors. There they donned improvised costumes and walked towards camera multiple times to get the shot. Local farmers and dog-walkers were very confused, not least because it was clear as day – all the wind and atmosphere was later added by ILM.