Australopithecus: Life In The Pliocene
The Pliocene World
Our World- 3.2 Million Years Ago
It is the mid Pliocene and many pieces of the jigsaw are coming together to create a world that would be familiar to our modern eyes. Africa, Europe and Asia are all fused and the Americas will soon join. The trend towards a colder, drier climate continues and grasses enjoy an explosive success. There are still tropical forests at the Equator, but a third of the Earth’s surface is now covered in some form of open grassland and here types of elephant, horses and antelope share the grazing just as they do today. Africa is the largest landmass to straddle the Equator and provides a retreat for many creatures escaping the advancing grasslands. One group of mammals forced to adapt to more open environments in the mid Pliocene are the tree dwelling primates. First the heavier, taller apes evolve, and then a species with a more upright stance that allows it to move quickly between trees and over open ground in the search for food. This is the australopithecine and in time, it will give rise to one of the most bizarre creatures the world has ever seen-ourselves.
Do Chimps Grieve In The Same Way As Humans
Death In The Family
It is a hot, still day and while most animals are resting in the shade a large porcupine is out in search of water. As he approaches an ancient acacia stand he stops to scratch at some of the many parasites that plague him. His long spines may save him from ending up on a lion’s menu, but they also prevent him from grooming properly and make him a magnet to ticks and fleas. He shakes and carries on through the open ground beneath the trees. Ahead he can smell and hear running water. The acacia are crowded round a crystal clear stream that tumbles over some large yellow rocks before spreading out and meandering among the parched boughs.
As the porcupine nears the banks he smells something else. Just upstream from him sit a group of australopithecines. These are large apes, but the porcupine knows that he can resist their attention. What stops him from drinking is the rancid smell of death.
Lying half in and half out of the stream, with the cool water lapping round her lifeless features, is an old female australopithecine. There are no apparent signs of violence, indeed, on closer inspection the poor condition of the animal suggests that she died of a prolonged illness, such as malaria. The other members of her group sit very quietly. A large male shuffles closer and leans over to sniff her. Satisfied that she is dead, he turns and wanders off into the forest to resume feeding. One by one the others follow him; they are all unusually quiet.
Finally, only one is left, a four year old male, who I shall call Blue. His dark eyes are fixed on the corpse and he lets out a long, whimpering sound. It is his mother in the river, and although these australopithecines form very sociable groups, without his mother to teach and protect him, his future looks bleak. He would probably have stayed by her for hours had not the sight of a large porcupine washing upstream scared him and sent him stumbling off after the rest of the group.
A Direct Ancestor
Many species of these bipedal apes lived in southern and eastern Africa between 4.5 million and 1.5 million years ago. The main animal featured in this hub is Australopithecus afarensis, one of the older and more lightly built species.
Evidence: Australopithecus afarensis is know from fossils found in Ethiopa, Tanzania and Kenya. This species includes the famous fossil named 'Lucy,' found at Hadar.
Size: Males 5 feet tall, females 3-4 feet tall.
Diet: Varied, including fruits, tubers, nuts and probably some meat.
Time: 3.9-3 million years ago.
A Bizarre Elephant
The deinotheres were gigantic but little known cousins of the elephants which flourished at the time of the australopithecines. Tusks in the elephant family have continually varied in shape and size as they have been used for different purposes. Wear marks on the downward curved tusks of Deinotherium suggest that they were probably used for stripping bark.
Evidence: Deinotherium remains, particularly their tusks and teeth, occur at all the major excavation sites in East Africa where hominids have been found, including Laetoli and Olduvai Gorge.
Size: Males 13 feet at the shoulder, females 11 feet 6 inches.
Diet: Browsed vegeatation and stripped bark.
Time: 20-1.5 million years ago.
A Highly Recommended Link
- john hawks weblog | paleoanthropology, genetics and evolution
The weblog of paleoanthropologist John Hawks.
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Home Sweet Home
The area of eastern Africa where the australopithecines live is a haven for wildlife. It is geologically very active, but the climate supports an abundance of animals and plants. Between the volcanic peaks is a mosaic of grassland savannah, open woodland and dense tropical forest. This variety of habitats is reflected in the range of animals that shelter here. Plains creatures such as antelopes, elephants and horses live close to forest dwellers like primates, bats and pigs.
The australopithecines are animals that have developed a unique way to move easily between these two habitats. They are equally at home clambering among the trees in search of fruit or digging in more open ground for roots, groups of australopithecines are dotted all over this area. The reason for their success lies in their adaptability. They are extraordinarily intelligent animals, constantly adjusting to situations and exhibiting highly sophisticated social behaviour.
The ‘acacia group’ of australopithecines formed about a decade ago when a larger community to the north split and three males and four females moved south out of the dense antrocaryon forest into the more open mahogany and acacia woods. With the death of the old female only one adult from the original seven is left- Grey. He has been the dominant male for the last seven years. With him there are now three other females, Babble, Berry and Blackeye and a large young male, Hercules. Babble and Berry both have young, with the newly orphaned male Blue completing the group.
Relationships within the group are highly political. Although Grey is still very much in charge, he knows Hercules is waiting to challenge him. It’s important for him to keep the support of the adult females and the loss of Blue’s mother, one of his most loyal supporters, has upset the balance. In the days after her death Hercules showed signs of aggression and this resulted in tension becoming widespread throughout the group.
One afternoon the apes move to the very edge of the woodland to feed on jackal berry bushes. They all arrive walking on two legs, another unique feature of these primates. It would appear that, since they spend so much time in the open, this posture allows them to move about more efficiently. It also makes them faster than their knuckle walking ape relatives and, since they are more vulnerable to large predators on the ground, this is important.
As is now usual, Blue arrives some time after the rest and has difficulty reaching the berries. Until a couple of weeks ago, his mother would have been there to assist him, but now, help isn't forthcoming as the other australopithecines ignore him. When he eventually finds some food Berry’s baby takes it from him, but he does not dare resist, through fear of Berry attacking him in retaliation. Another loss Blue must now overcome is the absence of the intense social bonding he experienced with his mother. While she was alive, he would spend large parts of the day sitting next to her while she groomed him. None of the other females in the group is able or willing to adopt a dependent, so he is going to have to learn to grow up very quickly.
Nearby on the open savannah, a herd of magnificent deinotherium are destroying a lone acacia. These ancient cousins of the elephants use their downward facing tusks to strip the bark off the tree and, as if that wasn’t enough, after they have eaten all the bark they can reach, they use their weight and short muscular trunks to push the whole tree over and strip the upper branches. Without the activities of deinotherium herds, the woodlands would be far more extensive.
The apes ignore the elephants while they cram their mouths with soft berries. Unusually Hercules does not join in the feeding. For a time he watches, then he breaks off a branch and starts dragging it round, shrieking and chattering. It’s a direct challenge to Grey. The older male ignores the show of aggression, but the females around him are getting nervous. Babble and her youngster have to run out of the way as Hercules works his way closer to Grey. But just as it looks as though are going to get out of hand. Blackeye starts hooting with alarm. The deinotherium have finished destroying the acacia and, attracted by the commotion, are heading towards the group. Grey stands up, grabs a dead branch and starts thumping the ground with it before heading off into the denser woodland. The females follow him and Hercules drops his branch and does likewise. Just before the huge proboscidean arrives to crush the jackal berry bushes. Blue gathers up some dropped berries and lopes off after Hercules.
Two days later the group are feeding near a large cascading waterfall. Babble is showing her daughter the peculiar delights of acacia sap, which australopithecines use like chewing gum. Blue sits close by, but is not included in the lesson. He is not well and has had a case of diarrhoea. Again, if he had the care of a mother she would show him that eating myrtle leaves is good for this condition. As it is, he will just have to survive without her. It’s desperately important that he starts to form his own social links within the group because, although they tolerate him, he needs to reinvent his role.
Suddenly Hercules, who has been in the lower branches of a tree, comes crashing down towards Grey, shrieking and waving vegetation. Grey stands up and both males puff out their chests and start shoving one another. The whole group jabber and call at this outbreak of violence. Hercules once again breaks off a branch and drags it around, but he is charged by Grey, who gives him a flying cuff around the head. While Hercules recovers, Grey runs to the edge of the stream and starts throwing pebbles and rocks at his opponent. Hercules is coming off worse and it is clear that Grey is not going to surrender his position without a fight.
As quickly as the violence started though, it ends. In triumph Grey mates with Blackeye, but in an interesting new development Babble goes over to groom Hercules. Grey may have won the battle but the war isn’t over.
Defending Their Patch
How Chimps Fight Over Territory
Time To Relocate
A ripe fig tree has drawn the acacia group to the edge of the forest in the northern part of their territory. These primates spend 60 per cent of their waking time feeding. While Blackeye and Grey climb among the branches to pick fruit, the rest sit round the base, feeding on the fallen ones. Blue sits next to Babble, holding out his hand for food. Australopithecine mothers usually care for their young for up to five years, so at four Blue is struggling to be independent. But Babble has her own youngster to concentrate on and ignores Blue.
The tree is near a river that runs out of the forest and on to the savannah. There are giant otters here that can attack and kill young australopithecines. Today there doesn’t seem to be any about, but instead a much bigger threat arrives in the form of six male australopithecines on the other river bank. They shriek wildly and throw stones at the acacia group. Grey reacts quickly, standing up, baring his teeth and waving his arms. The strange australopithecines are a hunting party intent on displacing or even killing others of their own kind. The acacia group must win this latest battle if they are to hold onto their territory. After a long series of challenges, Grey charges the other males, splashing across the shallow river and throwing stones. He is a large ape and four of the challengers quickly disappear back into the forest. But the other two stand their ground and Grey stops short of physical contact. Soon the four males reappear and all six charge Grey. He is instantly overwhelmed and receives blow after blow as he tries to retreat back across the river.
By now the acacia group are in turmoil, the females pick up their young and flee. Hercules offers the defeated Grey no help whatsoever as they run from their attackers. In all the chaos Blue is left far behind. He is lucky that none of the males find him, because they might well kill and eat him, but as the acacia group get further and further away his chances of survival are looking bleaker. He still hasn't learned to find food for himself and he would no doubt make a nice small snack for a leopard.
Footprints In The Ash
Last Of The Ancients
One of the last surviving chalicotheres, Ancylotherium was a built rather like a large goat, adapted to reaching up and browsing on vegetation that studded the plains of Africa, just as its ancestors had done all across the plains of Europe, Asia and North America.
Evidence: Sparse remains of Ancylotherium have been found at many of the most famous hominid fossil sites in East and South Africa, including Olduvai Gorge and Laetoli.
Size: 6 feet 6 inches at the shoulder.
Diet: Browsed vegetation.
Time: 6,5-2 million years ago.
How Australopithecines May Have Built Their Nests
On The Move
With only two adult males the acacia group have little chance of holding on to their territory for long. Over the next few days there are further confrontations and finally the group is forced out of the woodland completely. The open ground where they now find themselves is dangerous for them. They are still primarily wood and forest creatures and need trees to live in and as sanctuary from attack. So Grey immediately heads for another patch of woodland. As he does so, the group string out in a line to cross an open volcanic ash field. Although their ultimate aim is to find new territory, their immediate problem is water. They all need to quench their thirst.
Surprisingly, jumping in the footsteps the group have left in the ash, Blue is following only about 300 feet behind. He must have caught up with the rest of the group as they moved round their territory to escape their attackers, and so he did not miss their exit from the woodland. Despite all his hardship, Blue is showing remarkable resilience and as he bounces along behind the others there is even a suggestion that he is playing.
Grey leads them all to a waterhole just the other side of the ash field. A herd of gentle ancylotherium are already drinking there and they ignore the arrival of the apes. Fully grown, these animals are nearly 7 feet tall and weigh around half a tonne, far too big to feel threatened by apes. They are one of the last of a group of animals called the chalicotheres, some of whom were giant knuckle walkers. Ancylotherium browse on low branches, similar to goats, but are otherwise conventional four legged herbivores. The australopithecines gather next to the herd to drink while the two babies play at the water’s edge. The group show different approaches to drinking, some lower their heads to the water, others cup their hands and drink from them, but Babble gathers leaves and uses them to soak up water like a sponge.
It is because she is doing this that she is the first to spot the approaching male deinotherium. His smell and the weeping temporal glands on the side of his head immediately indicate he is in musth, a state of frenzied excitement, brought on by his eagerness to mate, this makes him a very dangerous animal to be close to. The ancylotherium quickly scatter, but the australopithecines have to head for a group of trees on the other side of the lake for safety. They run, but Babble’s youngster is still by the water and the deinotherium is approaching fast. The mother calls out, but the little ape is too frightened and confused to respond. As the rest of the group swiftly retreat to the trees. Babble remains on the ground desperate to reach her baby, but too afraid of the unpredictable giant to return to the water’s edge and collect him.
Her screeching is clearly disturbing the deinotherium and instead of drinking he heads for the trees where the group are. The baby is safe, but the rest of the australopithecines are now in trouble. Babble deftly swings into the treed as the deinotherium draws near. At first he just trumpets at them, shaking his head and displaying his saliva covered tusks. But then he rams the nearest tree violently. Although these are massive trees and he will never topple one, it is still time for the group to move on. The forest is quite open, but they move easily through the branches and were boughs do not connect they drop down to run between trees. Only Babble doesn’t follow Grey. She works her way sideways and then runs across and grabs her baby. As she flees into the woods the deinotherium is momentarily distracted, but he then goes back to pushing at the stout tree which is now empty of australopithecines.
Blue is late as usual, but on this occasion it allows him to witness the whole episode from a safe distance and take a drink. He watches the commotion while sitting next to a pile of deinotherium dung. Driven by hunger he sniffs it and then starts to eat it. This behaviour may seem odd and disgusting, but in fact it’s a good way of obtaining extra nutrients that the deinotherium’s digestive system could not deal with. It’s likely that he learned this behaviour from his mother. But when Blue sees the group head off into the woods, he stops feeding and skirts round the lake after them.
Around dusk the group stop to build nests, something australopithecines do every night. In heavily forested areas the nests can be quite elaborate, but here in this woodland they are very simple. An ape’s nest is his castle and no other ape, no matter where he appears in the pecking order, can disturb another’s sleep. Blue still has much to learn about constructing nests, but before his mother died he had at least started to build his own, although it still involves a lot of trial and error.
While he is pulling branches down around him to form a loose platform, his attention is drawn to Babble’s baby who is playing on a branch. He walks along the branch and sits close by watching her. The youngster starts to play fight with Blue, cuffing and wrestling with him. It is an important moment for the orphan, because it is the first time since the death of his mother that a member of the group has acknowledged him. Unfortunately he gets overexcited, the play becomes too rough and the youngster cries out. Babble is there in seconds, grabbing Blue and trying to bite him. The whole group is in uproar. Hercules joins in and luckily breaks it up before Babble can inflict real damage. Blue scampers over to his nest for sanctuary. Ironically, despite the violence of the confrontation, this was good for him. Both Babble’s baby and Hercules seem to acknowledge him as part of the group. This cannot happen too soon for Blue, he is looking very thin and is certainly not as large as he should be at his age.
One of the big sabre-toothed cats, with several species spread across North America, Europe and Asia as well as in Africa. It was built rather like a modern jaguar, but with more powerful front legs which meant that it probably ambushed its prey and used the front legs to hold it down firmly while it made a clean kill with its teeth.
Evidence: Dinofelis is relatively rare, but its remains are found in conjunction with hominid fossil sites.
Size: 3 feet at the shoulder.
Diet: Antelope, baboons and australopithecines.
Time: 5-1.4 million years ago.
The days pass and although the acacia group do not move far they take another couple of weeks to settle in a new territory. About 30 miles south of their original home they find an area dominated by pod mahogany trees. These are ideal for making nests in and can also have tasty fruit. There are no other australopithecine groups around and so there is a fair chance that they will do well here. However, it is very close to the savannah and there is a danger in this woodland that is not immediately apparent.
Late one afternoon Grey and the females find a cross berry bush. Its soft fruit is a favourite with the apes and they all drop down from the trees to strip it. Nearby are the burrows of a dwarf mongoose colony and while the group feed a hunting party returns. The mongooses rush around the australopithecines, greeting and rolling over each other, but ignoring the apes completely. These active little hunters know exactly what and what not to fear. Gradually they retreat down their burrows, but five or six remain above on look out duty.
At this point Hercules arrives, cradling an ostrich egg in his arms. Gently he hoots and rolls the egg on the ground, then scampers back and forth to attract attention. Grey conspicuously ignores him, but the others are curious. In particular, Babble wanders over to sniff the egg. After showing off for a while, Hercules comes back to the egg, carrying a stone. He thumps at the shell several times and, having created a small hole, dips his finger inside to pull out the yolk. Babble and Berry abandon the fruit and join Hercules for a taste of egg.
Grey is now getting angry. He picks up a stick and drags it around where Hercules and the others are feeding. The mongooses shriek and disappear down their burrow, but this is not because of the fight between the two males. The warning is there, but the apes are too preoccupied to notice. Blackeye is sitting alone by the cross berry bush as a huge pale coloured creature streaks across the ground towards her. She has no chance of escape.
The sabre-toothed cat, dinofelis, is an ambush predator with powerful front limbs and a crushing bite. Blackeye has no more than a moment to cry out before she is bowled over and pinned down. Attacking a large ancylotherium the dinofelis might have gone for the throat, but with the ape he just crushes her skull. It’s all over even before the rest of the group have time to react. Then, with an almost simultaneous screech from four throats, they scramble for the nearest trees. Shrieking in alarm and terror they race about the branches, shaking leaves and staring at the sorry sight below. The dinofelis adjusts his grip on Blackeye so that he has her neck in his mouth. Then he half lifts her and starts to drag her away from her distraught companions.
Big cats are the main predators of australopithecines, especially smaller species such as leopards, which can climb into the trees in pursuit of their prey. Dinofelis usually attack larger prey, but if this particular one develops a taste for apes then the group is in trouble. The sabre-tooth drags Blackeye to a large mahogany tree that leans over a deep limestone sinkhole and then, using his incredibly strong forelegs and neck, manages to carry her up into the lower branches. Despite his size and power the dinofelis knows that the smell of the kill will attract competition, particularly from hyenas. If he is outnumbered he can be chased off a kill before he has managed to eat his fill. In the tree he can eat the carcass in peace or leave it and return to it later until the whole kill is finished or has fallen into the sinkhole.
It is several days since the dinofelis attack and the group are sitting in some lower branches indulging in mutual grooming. Blue is grooming Grey, earnestly picking away at the hairs on the back of his neck. This is an enormous step forward for the youngster, it means he is beginning to establish himself and, although he is right at the bottom of the pecking order, he now stands a good chance of seeing adulthood. The death of Blackeye was a blow for all the group, but particularly for Grey. She was very loyal to him, and with her gone, his tenuous grip on power is slipping. Only a short distance away he is being watched by Hercules and, what is more worrying. Hercules is once again being groomed by Babble.
As if all of this were not presenting Grey with a difficult enough situation, a young female australopithecine suddenly appears out of the bushes below and climbs the tree opposite. She does not attempt to come too close, but it is clear that she is making overtures to join the group. This is quite normal, when females reach maturity they often swap groups, which helps to maintain genetic diversity and prevent inbreeding. The group pretend to ignore her, but in truth she is being closely watched. Soon Grey clambers down from the tree and walks across to investigate the newcomer. Like all females who move between groups she has just become fertile and is very submissive. Grey mates with her, but this doesn’t serve as an indication of her acceptance. In order to achieve acceptance she must learn the politics of the group and integrate herself with the other females before she can groom and feed with them.
Later in the afternoon the group are moving through the woodland and come across a recently killed ancylotherium, probably the work of the same dinofelis that killed Blackeye. Vultures and jackals are already fighting over what the cat has left behind. It is known for australopithecines to eat carrion, but they are very choosy about it, they will not touch anything that has been dead for any length of time, probably because of the danger of contamination. They like to see it being killed. However, on this occasion, Grey decides to go and investigate, picking up a stick and chasing the vultures away. Meanwhile Hercules takes the opportunity to mate with the new female. He makes no attempt to conceal what he is doing and it amounts to a direct challenge to Grey.
Grey comes charging back towards the group, dragging his stick after him and screaming at Hercules. All the females scatter, but Hercules stands his ground and the two males draw up to their full lengths and start to chest each other. The whole group are screeching as Hercules breaks off, climbs into a nearby tree and vigorously shakes the branches at Grey. The older ape then starts to lob stones at his rival. Unusually there is no sign that either male is going to back down quickly. For all his bravado Grey knows that Hercules is younger, larger and stronger than he is, the writing is on the wall. Suddenly Hercules leaps down from the tree and charges Grey, knocking him to the ground. This seems to be a turning point. Grey doesn’t get up so quickly and when he does he seems more reluctant to challenge Hercules. For the first time in seven years he tastes defeat. It’s the end of an era and Grey has to acknowledge that the group now belongs to Hercules.