The Africa of two million years ago is a crossroads in human evolution. Half a dozen or more different species of ape-men exist alongside one another. Each of them has exploited the environment in a different way and has developed their own strategy for survival.
'Blood Brothers' follows the lives of two species, Paranthropus boisei and Homo habilis who embody two alternative ways of ape-man life. Although heavyset, with distinctive gorilla-like faces, the boisei are gentle characters. They live within a strict social structure and are led by a dominant male whose strength and power holds the group together.
They are adapted brilliantly to the tough conditions in this dry arid land. Their huge teeth, four times the size of our own, and strong jaws mean they can eat the toughest vegetation. For them dried tubers and reed roots are rich pickings.
The habilis have taken a different approach to survival. They don't have the specialisms of the boisei but instead have developed into the archetypal jack-of-all-trades, inquisitive scavengers prepared to try almost anything to survive. Tough, active, gregarious and noisy, they are always on the move and always alert to the possibility of a meal. But in the near drought of the dry season the habilis are struggling. It seems as if their way of life cannot help them when conditions are tough.
However habilis have a secret weapon. They have come to use brainpower rather than brawn. They've learnt to work together to scare other predators away from food. They scavenge for meat and, perhaps most importantly, make basic stone tools - equipping themselves through their own efforts with the kind of specialist eating equipment creatures like the boisei have by nature.
But which strategy for survival will win out? Which of these ways of living is still present in us? As is often the case in our story, nature has a say: Massive geological turmoil means the habilis and boisei environments continue to change. The boisei's specialisms have locked them into one way of living, and when their niche no longer exists, neither can they. But the habilis can adapt to a changing world - their generalist trait lives on in us.
Why two million years ago?
We chose to set our next story two million years ago because the fossil evidence indicates that there were several species of upright-walking hominids around at the same time. During this period, many different species of animals were experiencing dramatic changes.
These adaptions happened because the plants in Africa were changing around 3 to 2.8 million years ago. Africa went through a process of drying, causing woodland to shrink back further and be replaced by grass. This in turn prompted new animals to evolve to exploit the new food sources, and new predators to evolve to exploit them.
The creation of the Himalyan mountain range dramatically altered rainfall patterns in East Africa, drying out Africa over many millions of years. But between 3 and 2.8 million years ago, changes in the Earth’s orbit made the seasons more extreme: The summers became hotter, the winters colder. This caused the polar ice caps to expand, locking up reserves of water and causing a drop in rainfall, drying Africa still further.
A whole host of features in their skulls tell us that Paranthropus boisei was a unique species. They were impressive creatures with dish-shaped faces and enormous molars that were four times the size of our own. Wear patterns on their tooth enamel show that they used these big molars to break down hard, gritty food. Chemical analysis of their teeth shows they must have been eating certain kinds of papyrus and bullrushes.
For all these reasons, it seems that boisei, if not a herbivore, had adapted to strongly favour a specialist diet of tough vegetation.
In our story, we suggest two reasons that boisei lived in a harem structure with a dominant male, rather than a more fluid social grouping. Firstly, the skulls of male boisei have a large saggital crest down their top and back, which is lacking in females. In modern-day primates, such as gorillas, this phenomenon - called sexual dimorphism - is usually seen in species where a male mates and protects a select group of females.
The second reason we employ the harem social structure is because it is usually found in primate species whose food is uniformly distributed, like the tough roots or shoots of vegetation.
Paranthropus boisei’s heavy jaws and teeth allowed them to eat the tough vegetation that other hominids and primates were not so well adapted to. But when the African environment changed again, they were too entrenched in their evolutionary niche to keep up with what was happening around them.
Although the details of many homininds are argued over by anthropologists, Homo habilis and its classification is particularly controversial. Many of the habilis fossils that have been found have been categorised differently by different anthropologists.
One important specimen is OH 7. Found at Olduvai Gorge in Tanzania, the hand bones resemble later species of the genus Homo, rather than the australopithcines. In another fossil, OH 24, the skull bones are thin and the brain case is larger than hominid predecessors. It also has a short, straight face with teeth that show it was an omnivorous species.
Generalists versus specialists
We know of at least half a dozen hominid species that existed at the same time in Africa, including a generalist called rudolfensis, which we feature in the film. We centre our story on boisei and habilis because they are the two best-recorded species at this time.
The name Oldowan comes from Olduvai Gorge, where Mary Leakey defined and described the tool-making industry. The stone tools come from the lowest rock strata at the site, which are close to two million years old. Although there is no hard and fast proof that habilis made the earliest Oldowan tools, these tools were found in the same fossil layers as this hominid. Homo habilis has the delicate hand bones to be able to manipulate them and the large brain capacity to make and use them. Scientists believe that stone technology evolved in parallel with the expanding brain and socialisation of Homo.
Professor Robert Winston meets Lucy, the first upright ape, and follows her ancestors on the three-million-year journey to civilisation. Broadcast in 2003, Walking with Cavemen combined special effects with the latest scientific theories, to show us what it really means to be human.
In the previous Walking with... documentaries, extinct animals were recreated with CGI and animatronics. For Walking with Cavemen, a slightly different approach was taken. While most of the animals depicted were still computer generated or animatronic, the human ancestors were portrayed by actors wearing makeup and prosthetics, giving them a more realistic look and permitting the actors to give the creatures a human quality.
Like its predecessors, Walking with Cavemen is made in the style of a wildlife documentary, featuring a voice-over narrator (Robert Winston in the British release, Alec Baldwin in the North American release) who describes the recreations of the prehistoric past as if they were real. As with the predecessors, this approach necessitated the presentation of speculation as if it were fact, and some of the statements made about the behaviour of the creatures are more open to question than the documentary may indicate.
Each species segment takes the form of a short drama featuring a group of the particular hominid in question going about their daily lives (the search for food, protecting territory, and caring for the sick and injured). The intent is to get the human viewer to feel for the creatures being examined, almost to imagine being one of them (a trait that the documentary links to the modern human brain).
Episode One: "First Ancestors"
In the first episode, we see Australopithecus afarensis, and focus on their evolved bipedality (walking on just rear feet - our legs). More specifically, the story follows the famous Lucy and her relatives, as they first develop a leadership conflict following the death of the alpha male due to a crocodile attack, and then are attacked by a rival troupe. The attack ends with death of Lucy herself, and her eldest daughter caring for Lucy's now-orphaned baby (her sibling), as a sign of the developing humanity in these "apemen".
Time: 3.2 Million Years Ago
* Australopithecus afarensis
Episode Two: "Blood Brothers"
The second episode leaps forward to a time when Paranthropus boisei, Homo habilis and Homo rudolfensis co-exist. H. habilis is depicted as an intelligent omnivore that is more adaptable than the herbivorous P. boisei. The two species are contrasted, with H. habilis being "a jack of all trades", while P. boisei are "a master of one" - i.e. they are specialized herbivores while H. habilis are generalized omnivores. Consequently, though P. boisei are able to eat termites, tall grasses and hard acacia pods in difficult times, they will not be able to survive in the future, when at the beginning of the next Ice Age the climate will change, and these plants will be gone for good. H. habilis, on the contrary, have become smart by eating carrion and bone marrow among other things, and evolving a basic social behavior, which is more firm than that of P. boisei, will continue to survive, until it evolves into Homo ergaster, seen in the next episode, who has developed these traits to a greater extent.
The episode also briefly shows the H. rudolfensis, remarking that albeit they are taller, they are very similar to the H. habilis.
Time: 2 Million Years Ago
Place: East Africa
* Paranthropus boisei
* Homo habilis
* Homo rudolfensis
Episode Three: "Savage Family"
In the third episode, Homo ergaster is depicted as the first creature to master the art of tracking. This was made possible because their diet has grown increasingly more carnivorous, and the nutrients in meat made them even smarter than H. habilis of the previous episode. They also begin to form into tribal societies, with genuine bonds between their men and women, though violence is still occurring.
The episode later shows H. ergaster spreading into Asia, becoming Homo erectus and encountering the enormous herbivorous ape Gigantopithecus, "the original King Kong".
However, for the next million years, H. ergaster is still very much an animal, following its instinct, but then, they are shown harnessing fire and beginning to break-away from their direct dependence on their environment. (This ties neatly into the next and final episode, which is centered on human mind and imagination.)
Time: 1.5 Million Years Ago - 500 000 Years Ago
Place: Southern Africa - China
* Homo ergaster
* Homo erectus
Episode Four: "The Survivors"
The fourth episode talks about the mental evolution of the humanity, as opposed to the physical in previous ones. First we leap forward to a time when Homo heidelbergensis is living in Great Britain. H. Heidelbergensis is depicted as intelligent and sensitive but lacking in the ability to comprehend an afterlife, or anything that isn't in the "here and now".
Next, the episode shows a life of a clan Homo neanderthalensis, how they lived and hunted, including the mighty mammoth during the latest Ice age. They are intelligent but still lack the imagination of modern humans.
Finally, we see modern Homo sapiens (represented by Bushmen) in Africa, who had to become imaginative and inventive to survive the long drought, and finally glimpse the cave painters of Europe, who had "evolved" the idea of the afterlife and the supernatural, and who are now ready to start the human history as it is now known (and drive-out the Neanderthals to extinction).
Time: 200 000 Years Ago - 150 000 Years Ago
Place: Europe - Africa
* Homo heidelbergensis
* Homo sapiens