Life of Mammals 

Three and a half million years separate the individual who left these footprints in the sands of Africa from the one who left them on the moon. A mere blink in the eye of evolution. Using his burgeoning intelligence, this most successful of all mammals has exploited the environment to produce food for an ever-increasing population. In spite of disasters when civilisations have over-reached themselves, that process has continued, indeed accelerated, even today. Now mankind is looking for food, not just on this planet but on others. Perhaps the time has now come to put that process into reverse. Instead of controlling the environment for the benefit of the population, perhaps it's time we control the population to allow the survival of the environment.

— David Attenborough, in closing
 

Episode 1: A Winning Design
The first episode gives a general overview of mammals before moving on to monotremes and marsupials. Attenborough begins in the high Arctic, where he contrasts the Arctic fox's ability to live there all the time (thanks to its dense coat of fur) with his own need for protective clothing, despite them both being mammals. From there, he travels to Australia to illustrate the evolution of the species with the help of the echidna and the platypus. Both creatures, unlike all other mammals, lay eggs — similar to birds and reptiles — and have been around for 100 million years. With an optical probe, the inside of a platypus nest is able to be shown for the first time. The defining characteristic of a marsupial is its pouch, inside which its young develop, having been born externally. Kangaroos and koalas are two examples that inhabit a warm environment, while the wombat demonstrates its ability to withstand a cold climate. Red kangaroos, in particular, are more at home in arid, desert-like conditions, while their grey cousins are sociable and prefer more temperate climes. The mammalian tongue is very adaptable, and those of numbats and honey possums have become greatly extended to enable the gathering of insects and nectar respectively. However, the most successful group of mammals are the placentals. Attenborough witnesses a wildebeest being born and explains both the dangers and advantages of this way of reproduction.

Episode 2: Insect Hunters
This programme discusses insectivores. Shrews are descendants of the earliest mammals, which were scurrying creatures that had a diet of insects. Their warm blood enabled them to hunt at night while dinosaurs slept; they nurtured their young and gave them milk. When the dinosaurs died out some 65 million years ago, the surviving mammals' inherent features meant that they could proliferate. These shrew-like creatures evolved: the elephant shrew is shown, alongside its prepared pathway of getaway routes; while others adapted further into species of mole, including the golden mole. The increased relative size of armadillos came about because they broadened their diet. Other animals grew larger owing to more of their favoured nutrition being available: these include the giant anteater and the pangolin. However, Attenborough hails the evolution of the bat — a winged mammalian insect catcher that can navigate using echolocation — as being "magical". The European brown long-eared bat switches off its echolocation and then uses its keen sense of hearing to detect an insect's location through its movements. He ascends 3 kilometres into the night sky over Texas to investigate why there should be so many bats at such a height. It transpires that this is also heights to which moths from the Tropics climb up as they migrate. Whereas the bats in Texas are forced to migrate in winter, Attenborough visits a cave in Canada where they stay all year round and go into deepest hibernation when the cold weather arrives. In New Zealand, bats seem to have reverted to the hunting techniques of their ancestors, and are shown tackling a weta on the ground.

Episode 3: Plant Predators
The next instalment looks at herbivorous mammals. The sloth is a leaf-eater, but it has compensated for the lack of nutriment in its diet by doing less (its reactions are a quarter the speed of a human's). This doesn't apply to all herbivores, which rely on bacteria in their stomachs to digest the leaves' cellulose. Plants can be poisonous, but Brazilian tapirs — the largest inhabitant of the South American rainforest — deal with them by eating a little of each species and then supplementing it with kaolin. The pika collects and stores plants to survive through the winter. In East Africa, via infrared cameras, Attenborough observes a herd of elephants squeezing into a pitch black cave and gouging the walls with their tusks to mine salt for their diet. Grazing animals, such as caribou and wildebeest, must migrate at the onset of winter and make long journeys to find new pastures. Despite its spiny fortification, the acacia is favoured by antelope, elephants and giraffes, which all have adaptations to reach its leaves. Smaller grazers are always at risk from carnivores: so they have developed the means to detect and evade them, and do so more often than may be supposed. A herd of buffalo are shown defending one of their number by charging the lions attacking it. However, the horns of antelope are primarily used for fighting each other to determine rank within their group and to maintain a breeding ground. Topi are shown doing so to the point where they are so exhausted that they easily succumb to a pack of hyenas.

(https://en.wikipedia.org/wiki/The_Life_of_Mammals)