I am not a scientist, and unlike some of my Christian brethren, I do not even pretend that I am. But I am a Christian and I like to think that I am reasonably intelligent. That being said, I was listening to an audio book while driving the other day, and the author made some radical statements about the evolution of Homo sapien (that’s you and me) and our relationship to some other creatures from the fossil record.
Because I like to think of myself as fair-minded, I listened intently to the arguments revolving around the development of bipedalism (walking upright on two feet) and brain size. In the audio book, the author made the case that bipedalism necessitated a smaller birth canal and thus the birth of relatively helpless infants who must be cared for by adults. This, he said, was the trade-off we made to come down from the trees around 2 million years ago.
What caught my attention was the connection between bipedalism and brain size. It is generally assumed by most paleo-anthropologists that our evolutionary ancestors first descended from trees and then developed larger brains.
In other words, we walked and then realized we needed to be able to chew gum at the same time. This is the core of the confusing story to follow.
This fundamental idea got me thinking about human origins and evolutionary models. How did we come to be, according to the theories and the fossil record? As a Christian, I believe we were created; but is there anything in the evolutionary model that might point to a better solution? So, I did some thinking and put it together for both of you who are reading this.
According to evolutionary theory, this is how you and I came to be. Rather, according to evolutionary theories (plural), here are two possible stories for how you and I came to be. Actually, they’re really part of one big, confusing story that makes little sense but is the standard story for our evolutionary development.
Story #1: Genus Hominini
Sometime around 7 million years ago (roughly 155,500 generations), a group of apes known to science as Sahelanthropus tchadensis had a small family problem. We don’t know what they fought over, but for some reason one group of these ape-like creatures went off to become fully bipedal while another branch decided to stay in the trees. The bipedal group went off to what is now Kenya and a million years later had became a genus all their own – Orrorin tugenensis.
Tugenensis was roughly the same size as its fellow-descendant from Sahelanthropus, the chimpanzee, but he apparently walked upright at least some of the time. They and another possible hominid ancestor, Ardipithecus, ran around the hills of Kenya for a million years or so before dying out or being replaced by another hominid species.
Ardipithecus had the curious problem of a strangely developed big toe. Although he lived in the shady forests of eastern Africa (now a savannah), he was bipedal – at least partially. He could not cling to the tree branches with his feet like his chimpanzee cousins.
What makes Orrorin, Ardipithecus, and Sahelanthropus unique from the other ape species of their time is that they had fully developed canine teeth, which seems to indicate that they were in same way omnivorous. Remains of apes of this time period show less canine development.
Sometime around 3.5 million years ago (give or take a few hundred thousand years), another hominid appeared in the area – Kenyanthropus platyops. This species developed something of a different look from those who came before him. He had high cheekbones and a flat plane beneath his nose bone, although he had a small brain, like others before him.
According to some authorities, Kenyanthropus eventually transitioned into homo erectus or “upright man.” But for the moment, let’s leave Kenyanthropus for a moment and dive into our second possible story, the story of the Australopithecines.
Story #2: Genus Australopithecines
In the forests around Lake Turkana, Kenya, a small ape-like creature now known as Australopithecus anamensis climbed out of the trees and starting fooling around down on the ground. We know virtually nothing about this Australopithecus except that he must have lived around 4.1 to 3.9 million years ago.
Anamensis shared the area, at least for the brief period of a few hundred thousand years, with another remarkably similar hominid known as Australopithecus afarensis. This particular creature, known today by the kindly name of “Lucy”, appears to have spent most of her time on the ground.
Lucy was not alone with the anamensis either, and that’s a good thing because they probably could have mated successfully given their genetic similarities. They were both contemporary with no less than four other types of Australopithecus – A. bahrelghazali, A. africanus, and A. garhi – and an additional four species that diverged from them, known collectively as Paranthropos.
While these latter species developed alongside Australopithecus, they remained distinctly apelike while the Australopithecines became increasingly more like humans.
As the story goes, the Australopithecines developed bipedalism and some kind of evasive behavior because they were forced to live in the savannahs as the jungle steadily retreated southward due to the developing ice age in the northern latitudes.
Eventually (around 2.5 million years ago), Australopithecus garhi began to develop tool-making and compete with the other Australopithecines for control of their area in Africa. For some unknown reason, however, garhi was not successful and died out without contributing to the human genetic line. It was left to another, distinct genus and species, to bring tool-making into the human line – Homo habilis.
Around 2.5 million years ago, some form of Australopithecus – possibly afarensis or africanus – developed a larger cranial capacity than his fellow hominids. It is not impossible that he then stole the tool-making technology from the A. garhi and became the dominant hominid species.
His Latin name, habilis, means “handy man” because his hands were much more tactile than previous species. He also had enough physical differentiation from Australopithecus to warrant being classified under a new genus – homo, or “man.”
Whether descended from Australopithecus or Ardipithecus, this new species was a force to be reckoned with. Until recently, most paleoanthropologists believed that H. habilis eventually evolved into Homo erectus, but information has come to light that now leads them to believe that habilis and erectus probably co-existed at least for a time.
Although a relative genius when compared to your average Australopithecus, H. habilis simply did not have the smarts to use the tools he made for anything other than basic things. Apparently, the species was one of the primary prey of the dinofelis – a large predatory cat – but never thought to use their tools as weapons against their predators. One imagines a troop of H. habilis throwing down their stone axes and running like bandy-legged, hairy school girls at the sight of the great cat. Such a race is not long for this world, and before too long, they passed into extinction.
In their place rose Homo erectus, whose brain capacity was significantly larger than H. habilis and who figured out that one could use a stone axe most effectively on the skull of a dinofelis as well as to cut down trees.
While the two species shared the continent of Africa for half a million years, erectus eventually emerged from Africa while habilis never did – possibly because H. erectus also figured out that one could also use a stone axe effectively on the skull of an Australopithecus or H. habilis.
Between H. habilis and H. sapien, there are no fewer than fourteen names species of hominid. Just how distinct they were from modern man (Homo sapien sapien) is hard to tell. One test showed that one group (H. erectus) is 99.5% the same while another (H. neanderthalensis) is more distinct from modern humans than a zebra is from a horse. Regardless, all of the Homo species are remarkably similar.
Around 2 million years ago, evolution took away most of our body hair (but left it in the most inconvenient places. Along the way, we invented fire and warm clothes because we lost our hair.
About 1.6 million years ago, we evolved dark skin. Then about 60,000 years ago we evolved light skin. Somewhere in there, someone got offended by the color of someone else’s skin and invented bigotry.
And somehow, we’ve been fighting about land, women and money ever since.
If we go all the way back to Australopithecus or Sahelanthropus, then human beings have made some remarkable evolutionary leaps in the last couple of millions of years. Forget the development of language or advanced technology. Here is just a brief list of changes our bodies have made:
- Bipedal locomotion requires significant shifting of load-bearing. It requires the development of two opposing curves in the spine for erect movement, the flattening of the foot, the narrowing of the hips, and the development of shorter upper limbs. Because the weight of the body is carried entirely on the feet, smaller bodies, greater balance and a tremendous amount of energy expended for the restoration of joints and tendons.
- Increased brain capacity means that the creature must consume tremendous amounts of food to power it. High mental activity is extremely energy-intensive, as well as requiring copious quantities of proteins. This in turn necessitates an unspecialized diet. We must be able to consume both animal and plant materials. And this requires the development of a generalized tooth and mouth structure as well as the development of symbiotic relationships with the bacteria necessary to digest the complex proteins and materials in animal meat.
- Birthing processes must be altered where bipedalism and increased brain capacity become part of life. The birth canal is narrowed when a creature is bipedal, which requires that infants be born with only partially formed brains and flexible skulls. This in term requires the development of an advanced infant period when the infant is dependent upon the mature adults.
- Pregnancy is very complex for bipedal humans – far more complex than for apes. The bipedal human female’s narrow hips and upright position require that the child be carried in a very awkward position. It creates back pain, pressure on the bladder and a multitude of other complications that any pregnant woman will explain in detail.
- Tool making requires the development of advanced manual dexterity. This is tied to brain capacity but also requires a re-alignment of the tendons, ligaments and bones of the hands as well as the development of a specialized musculature in the arms.
And Now, the Big Question
All of this leads to one very, very big question. Why would we go through all the trouble of this development?
Being bipedal has some advantages of course, but how could they possibly be greater than the disadvantages? If having our hands free so we can throw a rock at a cougar really worth all the trouble?
Bipedalism is just one of those things about the human body that makes no evolutionary sense. If life were truly based on survival of the fittest, why wouldn’t we have reverted to being quadrapeds? Why didn’t we maintain at least some of our arboreal traits? Humans are most definitely NOT good climbers. We require tools and our intellect for any kind of climbing.
While our increased brain capacity has allowed us to build human civilization, why would we ever want to do that in the first place?
What would motivate our evolutionary ancestors to advance their intellect as they would have had to? Why would we develop the capacity to come up with ideas like empire building, religion or pay-per-view wrestling? There was no evolutionary necessity for the intellectual level of Homo sapien sapien.
We might be able to make some valid arguments for the adoption of bipedalism. Some paleo-anthropologists believe it developed because it was easier to retrieve food, others credit climatic changes and the requirement to move on flat ground quickly to avoid predators. Another theory is that bipedalism was developed to protect smaller hominids from other creatures. Standing on two feet is a way of threatening other animals, thus the early bipeds might have developed the permanent posture to oppose attack.
There are any number of theories, and they are being added to almost daily. One particularly effective theory is that bipedalism developed so that the hominids could better regulate their body temperature. By raising the greater part of their surface area away from the ground, they could remain warmer in the cold times of the year and receive greater cooling during the hot periods. Less of the surface area of the skin, exposed because of the loss of most of our body hair, would receive direct sunlight as well.
But why would evolutionary processes result in bipedalism with all its drawbacks? Just the load-bearing issues alone would seem to be enough to justify at least some more modification of the human body that we have not seen.
For example, why aren’t our feet proportionately larger to provide greatest stability? A bipedal human is incredibly unstable (as I discovered when I tripped down the stairs to my office this morning). Why did we have to lose some of the things we supposedly lost?
And that’s why I believe in creation
This is why the evolutionary tale you have just read does not make sense to me. Forget the infinite complexity of the human eye or the compromises necessary to structure even our digestive or immune systems for the vastly complex symbiosis with some microscopic organisms and warfare with others. Forget the inefficiency of our lungs to absorb oxygen and our virtual inability to exist outside of a very small margin of temperatures due to all the mistakes evolution must have made in making us “the fittest.”
In order for us to be what we are, we could not be the product of a refining process of nature. We are anomalous as a race, as a species. We shouldn’t – no, couldn’t – have survived as the fittest.