We all realize that us humans have some sort of relation to apes and chimpanzees, but what evolved us from them to becoming bipedal hominids? In this essay I will be inculcating you about the evolution of humans, the captivating discovery of Lucy, an Australopithecus afarensis, and how her uncovering of a new species is so important to our advancement. Lucy is our oldest, most complete human ancestor and it lead to a controversial change in our view of human origins.
Lucy is a 3. 15 million year old female hominid, of the genus Australopithecus, whose skeleton was uncovered on November 24, 1974 by Donald C. Johanson and Tom Gray in the Hadar region of Ethiopia. Donald Johanson’s first discovery consisted of a few pieces of a knee bone. He sent the bones to Owen Lovejoy, who was an anatomist and part-time forensic expert. He then examined the bone fragments and concluded that they appeared human, that the joint could “lock”, which meant the animal could walk upright. This was an important discovery showing an ancient bipedal creature.
They named their discovery, “Lucy” in reference to the well-known Beatles song “Lucy in the Sky with Diamonds”, which played over and over as they celebrated their findings. While only 40% of the skeleton was found, this uncovering of Lucy was very fascinating and answered many questions to our human evolution because it was the missing link between apes and the upbringing of hominids. The discoverers called Lucy, Australopithecus afarensis which stands for “southern ape of the Afar region”. This genus was one of the earliest species of hominids; the family of bipedal primates also includes homo hablis and homo erectus.
While Australopithecus and Homo species vary in many ways, both hominids share common characteristics that define them as a group. The most distinct of these traits is bipedal locomotion, which means they could walk upright instead on being on all fours like apes. The particular and revolutionary characteristics of Lucy is that she had a small skull, a bipedal knee structure, molars, and front teeth of human form and size. Lucy’s skeleton proves that her kind was bipedal by the shape of her pelvis and the angle the femur takes from the hip socket to the knee joint.
From her waist down she was hominid, and from her waist up she was still ape, as her skull was still the size of a chimpanzee. Her brain size varies in range from 365 to 385 cubic centimeters and had hand and motor cortex. Her species has a prolonged mouth, strong brow line, and a small forehead. She stood about three and a half feet high and weighed 60-65 pounds. The males were about twice the females size ranging from four to four and a half feet tall. This species also had about 100-120 different calls, hand gestures and signals.
This suggests a intricate social and mating system. Evidence shows that she was probably young but fully mature when she died of natural causes. Her corpse is likely known to have sunk into a lake and over millions of years, the lake dried up, buried, and harden her bones which eventually fossilized them and preserved them for us to discover. The following year, again at the famous site of Hadar, Ethiopia, Donald Johanson’s team made the ground breaking discovery of the fossilized remains of some 13 individuals, known as the “First Family”.
They believed that at that time, there was a mud slide that buried and killed tons of these creatures, in all age range, from babies to adults, both male and females. This was believed to be the oldest evidence of human ancestors living in groups. It had also provided us with much more understanding of their lifestyle and habitat. Lucy lived at a time when the Hadar region was not a desert environment like it is today. Instead, it was thought to be more like a woodlands and savannah domain.
A. farensis, was not totally ape and yet not quite human, is thought to have probably lived in a variety of habitats. Having evolved into being bipedal as an adaptation to living in the open areas, like grasslands with few trees. They were thought to feed for seeds, berries, fruit, tubers, nuts and termites. The benefit of being able to walk upright gave them the advantage of free hands to grab food or carry their young, looking over high grassland, and developing a bigger brain. Unfortunately for them, they had long dry seasons with no rain which made the food source scarce.
Without bipedalism we wouldn’t be able to develop into the hominids that we have become. The Hardy Weinberg’s equation is important for the concept of population genetics. In order for Hardy-Weinberg’s equilibrium of no evolution occurring to work, the following seven conditions must be met: no mutations must occur so that new alleles do not enter, no gene flow can occur, random mating must occur, everyone produces the same number of offspring, the population must be large so that there is no genetic drift, natural selection is not occurring, and all members are breeding in the population.
This equation does not work with humans because we do not randomly mate. Usually individuals choose a spouse who has positive attributes that they like, which can include personality, taste, attractive, good with children, intelligence, sometimes race/color, height, humor, etc. In Lucy terms they would want someone who is a good hunter, provider, and smart but they wouldn’t get that option of being picky because they couldn’t travel very far to selection their peculiar mate.
Also, natural selection happens all the time as well as mutations but most are not harmful. So if you were to apply this to the A. afarensis, the majority would disprove this equation. A. afarensis were also good at tool making. They used horns and bones as tools but not as weapons, as many people though they did. Also, they would use some stone tools that were known to be the breaking dawn to human technology. Their main predators were “big cats” such as lions and leopards. They had little to no protection which made them easy prey.
Leopards were excellent climbers but they could not climb as well as apes which made it hard to escape. Also the lions are very patient creatures, so they would wait under the tree until they would could down and then they would eat them. Eventually, the robust A. afarensis, a. boisei, a. robustus and a. aeithiopicus would go extinct but the gracile Homo Habilis, which was discovered 2. 6 million years ago by Lewis Leaky, would go on to become our ancestors. In Africa, some of the animals that relied on forest died out because it was too dry.
For example, during this period Lucy had disappeared because this species cant survive in that situation. But other species evolved by exploring different dietary sources that were available in that time. For example, many evolved physical adaptations to graze on the new species of plant life called grass that colonized the deforested terrain. The same seems to have happened to our ancestors, who had previously relied on forest foods such as soft fruit. We just kept evolving as the millions of years went by and adapting to new environments.
In this essay, as you can see, Lucy was an astonishing discovery and was the missing link to our upbringing. This species was bipedal and hominid from the waste down, ape like from the waist up. They were also smarter than chimps with their different hand and motor cortex, their tool use, and brain size. Without the constant concept and knowledge of evolution occurring, our species would have never of came about but we are very fortunate for this discovery and to be who we are in this world today.