MAKAME.M.MAKAME: April 2012

The Evolution of the Human

History of Man
SPECIES
TIME PERIOD

Ardipithicus ramidus
5 to 4 million years ago

Australopithecus anamensis
4.2 to 3.9 million years ago

Australopithecus afarensis
4 to 2.7 million years ago

Australopithecus africanus
3 to 2 million years ago

Australopithecus robustus
2.2 to 1.6 million years ago

Homo habilis
2.2 to 1.6 million years ago

Homo erectus
2.0 to 0.4 million years ago

Homo sapiens archaic
400 to 200 thousand years ago

Homo sapiens neandertalensis
200 to 30 thousand years ago

Homo sapiens sapiens
200 thousand years ago to present

The times of existence of the various hominid shown in the chart above are based on dated fossil remains. Each species may have existed earlier and/or later than shown, but fossil proof has not been discovered yet. There is also dispute concerning many overlapping species, for example, the overlap between Homo habilis and Homo erectus. It could well be that the two are continuing examples of the same species. The same dispute exists with Homo erectus, Homo sapiens archaic and homo sapiens sapiens. If all species have been discovered and the lineage of man lies within them, the most probable lineage would include all but the robust Australopithecines and the neandertal.

The following chronology is abbreviated:
The earliest fossil hominid, Ardipithecus ramidus, is a recent discovery. It is dated at 4.4 million years ago. The remains are incomplete but enough is available to suggest it was bipedal and about 4 feet tall. Other fossils were found with the ramidus fossil which would suggest that ramidus was a forest dweller. A new skeleton was recently discovered which is about 45% complete. It is now being studied.

A new species, Australopithecus anamensis, was named in 1995. It was found in Allia Bay in Kenya. Anamensis lived between 4.2 and 3.9 million years ago. Its body showed advanced bipedal features, but the skull closely resembled the ancient apes.

Australopithecus afarensis lived between 3.9 and 3.0 million years ago. It retained the apelike face with a sloping forehead, a distinct ridge over the eyes, flat nose and a chinless lower jaw. It had a brain capacity of about 450 cc. It was between 3'6" and 5' tall. It was fully bipedal and the thickness of its bones showed that it was quite strong. Its build (ratio of weight to height) was about the same as the modern human but its head and face were proportionately much larger. This larger head with powerful jaws is a feature of all species prior to Homo sapiens sapiens.

Australopithecus africanus was quite similar to afarensis and lived between three and two million years ago. It was also bipedal, but was slightly larger in body size. Its brain size was also slightly larger, ranging up to 500 cc. The brain was not advanced enough for speech. The molars were a little larger than in afarensis and much larger than modern human. This hominid was a herbivore and ate tough, hard to chew, plants. The shape of the jaw was now like the human.

Australopithecus aethiopicus lived between 2.6 and 2.3 million years ago. This species is probably an ancestor of the robustus and boisei. This hominid ate a rough and hard to chew diet. He had huge molars and jaws and a large sagittal crest. A sagittal crest is a bony ridge on the skull extending from the forehead to the back of the head. Massive chewing muscles were anchored to this crest. See the opening picture of an early Homo habilis for an example. Brain sizes were still about 500cc, with no indication of speech functions.

Australopithecus robustus lived between two and 1.5 million years ago. It had a body similar to that of africanus, but a larger and more massive skull and teeth. Its huge face was flat and with no forehead. It had large brow ridges and a sagittal crest. Brain size was up to 525cc with no indication of speech capability.

Australopithecus boisei lived between 2.1 and 1.1 million years ago. It was quite similar to robustus, but with an even more massive face. It had huge molars, the larger measuring 0.9 inches across. The brain size was about the same as robustus. Some authorities believe that robustus and boisei are variants of the same species.

Homo habilis was called the handy man because tools were found with his fossil remains. This species existed between 2.4 and 1.5 million years ago. The brain size in earlier fossil specimens was about 500cc but rose to 800cc toward the end of the species life period. The species brain shape shows evidence that some speech had developed. Habilis was about 5' tall and weighed about 100 pounds. Some scientists believe that habilis is not a separate species and should be carried either as a later Australopithecine or an early Homo erectus. It is possible that early examples are in one species group and later examples in the other.

Homo erectus lived between 1.8 million and 300,000 years ago. It was a successful species for a million and a half years. Early examples had a 900cc brain size on the average. The brain grew steadily during its reign. Toward the end its brain was almost the same size as modern man, at about 1200cc. The species definitely had speech. Erectus developed tools, weapons and fire and learned to cook his food. He traveled out of Africa into China and Southeast Asia and developed clothing for northern climates. He turned to hunting for his food. Only his head and face differed from modern man. Like habilis, the face had massive jaws with huge molars, no chin, thick brow ridges, and a long low skull. Though proportioned the same, he was sturdier in build and much stronger than the modern human.

Homo sapiens (archaic) provides the bridge between erectus and Homo sapiens sapiens during the period 200,000 to 500,000 years ago. Many skulls have been found with features intermediate between the two. Brain averaged about 1200cc and speech was indicated. Skulls are more rounded and with smaller features. Molars and brow ridges are smaller. The skeleton shows a stronger build than modern human but was well proportioned.

Homo sapiens neandertalensis lived in Europe and the Mideast between 150,000 and 35,000 years ago. Neandertals coexisted with H.sapiens (archaic) and early H.sapiens sapiens. It is not known whether he was of the same species and disappeared into the H.sapiens sapiens gene pool or he may have been crowded out of existence (killed off) by the H.sapien sapien. Recent DNA studies have indicated that the neandertal was an entirely different species and did not merge into the H. sapiens sapiens gene pool. Brain sizes averaged larger than modern man at about 1450cc but the head was shaped differently, being longer and lower than modern man. His nose was large and was different from modern man in structure. He was a massive man at about 5'6" tall with an extremely heavy skeleton that showed attachments for massive muscles. He was far stronger than modern man. His jaw was massive and he had a receding forehead, like erectus
.
Homo sapiens sapiens first appeared about 120,000 years ago. Modern humans have an average brain size of about 1350 cc.

History of Man - an Expansion

This section is a narrative based on the physical evidence in the introduction above. It is speculative, but it is believed that any reasonable alternative would lead to the same conclusions. The author solicits other opinions.

Evolution appears to work in bursts of activity. A species may survive for a very long time, even millions of years, with relatively little change, then suddenly, seemingly overnight, a variant species springs from it. Several such cases are evident among the hominid. When populations are large, species drift is very slow, regardless of species. Evolution works best when a small population of a species becomes isolated and faced suddenly with new hazards. The environment provides early and quick death to quickly weed out deleterious mutations and the small population provides a small gene pool across which helpful mutations may quickly spread.

This is the manner in which the first hominid, the walking ape, appeared. Although no one knows what specifically happened or where, a small pocket of primates were somehow isolated in an area where there were no cats (the main primate predator) and the food supply was short, perhaps even dwindling.

In warmer and wetter times, huge forests abounded across Africa. Both the ancient primates and felines were widespread. Then the climate changed. Forests dwindled. Patches of forests became isolated, causing animal interchange to become quite difficult. In most such patches, both primate and feline survived. The shortage of food, perhaps growing worse daily, drove some of the primates to the forest floor in search of food. There they became food for the cats. Life was too grim and short for a new ground dwelling primate species to develop.

But somewhere there was an unusual valley, one completely isolated from all the others, and something there eliminated the cat. Perhaps it was a disease. Perhaps it was a famine of all animal life, with the sole animal survivor being the primate. There must always be a large numerical ratio between food supply and predator. Perhaps it was a small valley, too small to support a large enough cat gene pool for the cat survival, but large enough to support bare primate survival. Or, more likely, the small valley was over-harvested by the cats to the point that only the primates, safe high in the trees, survived, and the cat was starved out of existence. The primate in that valley was then able to spread safely to the forest floor. The walking ape was born. The original primate species still ruled the forest canopy, while this new species, in the absence of felines, was dominant on the forest floor.

Then the climate changed, reopening the valley for the transit of both primate and feline. The tree-top primate rejoined his fellows and their gene pools blended. The feline was re-introduced to the valley. The bipedal ape on the forest floor was introduced to his new predator. If that introduction had been sudden, the bipedal ape could not have survived. Perhaps there were other valleys in which that actually happened. Luckily, in this one, it was slow, and the walking ape had time to adjust to his new danger. He formed defensive groups and developed defensive strategies.

That first hominid was Ardipithecus Ramidus. He lived on the forest floor. His close cousin, the primeval ape Ramapithecus, lived overhead. Ramidus had become a herbivore. Ramapithecus was an omnivore. Ramidus had feet on one end. Ramapithecus had hands on both ends. They were about the same size and had about the same intelligence. When the predator came, Ramapithecus escaped into the trees. With four hands he could out climb even the ancient leopard. In spite of the leopard, ramidus had to stay in the forest, being on the open plains was certain death. He was neither fast enough nor strong enough to handle the big plains' cats. While in the forest, ramidus could at least jump into a tree and escape the big ground cats, but he was still easy prey for the leopard. The death rate, especially among the children, was high. A pregnant woman had no chance at all. Something had to change. Ramidus learned how to cooperate in defense and he learned how to use a club. His culture became more restricted and structured.

The idea of a club was not new. Modern chimps will use one to beat on the ground in trying to drive off an interloper. The chimp does not need to learn how to use one well because he can always take to the high trees. Chimps will even cooperate in driving off interlopers by jumping up and down and screaming. They do not need to learn how to cooperate in fighting. They can always take to the trees. Ramidus did not have that choice.

Ramidus now had two things that kept him out of the trees in times of danger: his feet and the club. When the leopard came, he had no chance without the club whether he met the cat on the ground or in the tree. Climbing a tree in a hurry with two feet that cannot grasp anything and a club in one hand while trying to escape from a big cat would be an exciting experience. His women and children had no chance at all without his protection on the ground. Ramidus learned to get shoulder to shoulder with his friends, club at the ready, in front of the women and children, and stand his ground, no matter what the animal was. Now he did not have to live under the trees. He could live anywhere he pleased. They moved out on the plains.

Meanwhile, ramidus was also having deep trouble trying to make a living. He was a herbivore, the available food was coarse and hard to chew and his chewing apparatus had been designed to fit the needs of an omnivore who ate much fruit. The women, especially, were having real problems in caring for the children while foraging. The life style was brutal, and the death rate was high. Evolution loves a high death rate.

Evolution had few options. Ramidus could not return to the jungle. He was built wrong. He was structurally too slow to convert to a plain's predator. Besides, he was primarily a vegetarian and did not have the physical equipment to tear meat off his prey. Birth rate increases would require major physical changes. Only cultural changes were available. The women needed more time to take care of the children and the children would fare better if they did not need to be out on the plains. The males needed to take more of the burden. The tribe needed a safe haven for the women and children, preferably one with some protection from the weather. The old men could stand guard and the young ones could take their clubs with them and forage. Since they were bipedal, they had two arms to haul the food back to camp.

By the time Australopithecus afarensis appeared, some structural improvements had been made. His head was proportionately larger with a much improved eating apparatus, with molars that were much larger. The size of the canine teeth had diminished (evolution diminishes things not needed). His jaw was heavier and had huge chewing muscles attached. The male was also a little taller and heavier and the female was smaller because of their differing roles. A slight brain size increase provided improved social interaction. With the following Australopithecus africanus, they survived, in balance with nature, for almost two million years. Still, life was short, child mortality high, and hardship was constant. Evolution had honed the species to fit the environment and was now in balance. The people were tough, hard-working and resilient. Man had joined the other plains' animals in a balance with nature that appeared stable (not fun, but at least survivable). Many other plain's animals had also reached a stability in their evolution, one that exists to this day. If something had not happened to upset this balance, man would still be there today, mingling with the gnus and wildebeests.

Several things happened to spur further development. With their stronger culture, they could survive the plains better than the other herd herbivores. Their population grew. Competition was high for food. Other species branched off: Australopithecus aethipicus came first, followed by rsobustu and boisei. These were bigger and tougher competitors for the same food supply.

Somewhere along in that last million years of the reign of africanus, someone sharpened a stick, perhaps to use to dig roots, and discovered that a spear was a much more effective weapon for some uses than a club. A club is a good defensive weapon. When a club is used against an animal other than man, it is immediately available for another swing. It is not too good against another man. He will usually grab it on the way in and the advantage is lost. The aim of a club is usually to discourage, not to kill, and it is more effective against an animal than a man. A spear is an offensive weapon. It has only one purpose: to kill. Still, though skill is present in its use, it often sticks in the adversary and is torn from the hands when the adversary twists away. Looking bare-handed into the eye of a tiger with an out-of-reach spear sticking out of his shoulder is not healthy. The tiger gets down right irritated under such circumstances. Smacking him up side the head with a club, on the other hand, leaves the defender still armed. The spear works best in sneak attacks. Stalk and kill is spear territory. A few good men, working as a hunter-killer team, could now hunt and kill any animal on the plains, including other men.

Life became even more precarious, the favorite working ground for evolution. The greatest dangers that man now faced were other men. When man goes against man, and the weapons are the same, cunning is usually the deciding factor. A spear is a great equalizer in size, so growing bigger was not as effective as a survival move as growing smarter. Unfortunately, becoming more vicious was also effective. The docile hominid cow of the plains became a warrior. His culture was now much more complex, one that needed careful planning and leadership. This required intelligence and language.

Homo habilis was the transition man. Starting with a 500cc brain, it grew to a respectable 800cc. Habilis developed from a brutish and dim-witted herd animal to a competent man. The Broca's area in his brain became developed showing the existence of a workable vocabulary. He invented the use of fire for cooking, warmth and keeping wild animals at bay. He invented the stone axe. He also may have eliminated the last of that big tough robustus and boisei bunch. For some reason they disappeared about that time. For sure there was no one else on the plains who could have done them in.

Then, about 1.8 million years ago, Homo erectus came: mighty warrior, skilled hunter, inventor, far-ranging explorer and king of all he surveyed. The size of a modern human and standing as straight, he developed a 1250cc brain, very close to modern man. Along the way he developed many new tools and weapons, invented clothing, and traveled out of Africa, the first hominid to do so. He went across southeast Asia, into northern China and south to Java. He was now an omnivore who ate mostly meat, both animals and fish. He cooked his food. Evolution had noted the softer food, and degraded his magnificent chewing apparatus. By the end of his reign, his molars and jaw had shrunk to almost that of modern man.

The culmination of man's evolution was Homo sapiens (archaic). It has been down hill ever since. He came about 300,000 years ago, straight and tall, muscular, hardened and practical, with almost a full size brain, the result of four million years of evolution. Humankind was now a veteran of millions of deaths and countless hardships, with a population so small that mutations spread rapidly. His gene pool had little variability. Natural selection (death and misery) had kept him pared. Only the strongest, the most cunning, and the most stubborn survived.

Then came modern man, an anticlimax, about 120,000 years ago. From this point on his inventive mind would devise method after method to ease his lot. He would remove his enemies without compassion. He would learn to enslave other animals and even other men. He would greedily take from the world around him and from those who were weaker. He would make his life easier, and evolution would degrade him to match.