Hominids

What evidence shows the changing from the early hominids to the modern humans? Throughout the human evolution body parts like legs and harms have changed for the better. By the early hominids being biped, meaning they are able to stand and even walk on two feet, it helped them to be able to do more things like getting around more and help with their tool making and hunting. A lot of the fossils discovered were found in the Great Rift Valley in East Africa, which contained many different lakes and small rivers. For many years researchers have been finding new species. These species have been named Australopithicus, robust australopithecines , Orrorin tugenensis, Homo habilis, Homo erectus, neanderthal, and Homo sapiens. These early

Foreheads began to develop in the later members of the species, most likely as a result of an expanding frontal lobe (that part of the brain that we believe controls many of our higher functions such as reasoning, foresight and concentration) (Johanson and Shreeve 1989). Homo erectus had a lighter jaw than did Homo Habilis (Johanson and Shreeve 1989).

We share almost 99 percent of our genetic material with chimpanzees. Yet we have several traits that are very different. Two legged walking, or bipedalism seems to be one of the earliest of the major hominine characteristics to have evolved. To

Homo Heidelbergensis: Lower half of skull pops out more than the rest of the ‘homo skulls’

In the Article “Redrawing Humanity’s Family Tree” by John Noble Wilford, describes how two different skulls challenge the theories of human origins and migrations. The Central African skull, that dates back to nearly 7 million years ago, was assigned to a whole new genus and species because of its apelike and evolved hominid species. The 1.75-million-year-old Georgian skull shows evidence that the first hominids may have been intercontinental travelers who set motion the migrations that occupied the whole planet. Finally a third skull was found that is the same age and shares a resemblance but, the size of the skull suggests that the brain was smaller than expected for H. erectus.

According to Chimpanzee, an example of a homologous structure it shares with its descendants is its relatively large skull. As the animals became more evolved their skull shapes started to change to accommodate for a larger brain. This size difference is shown in Figure 2 because you can see the difference in the brain and skull size of the chimpanzees (bottom) and humans (top) (Chimpanzee). This is because Cranium size is determined by brain size and recent evidence by (Dumas, 2012) shows that this is likely determine by a protein domain called DUF1220. DUF1220 is a domain, a sub section of a gene, which is about 65 amino acids long and expressed mostly in neurons (DUF1220). Research (Dumas, 2012) shows that more copies present in the genome the larger the brain size is in that animal. Humans have 270 copies and the trend goes down from there with Chimps having 125, Gorillas 99 and marmosets 30 and mice just one (Dumas). This research shows the reasons hominids increased in brain size is because there was a mutation that increased the amount of DUF1220 in their lineage which led to gradually larger brain sizes. Since the Chimps split off (Figure 1) before this mutation their brains did not increase in size; hence the reason they are still similar to the common ancestor of both chimps and humans.

       In the article, "Brain ontogeny and life history in Homo erectus" by Steven R. Leigh discussed Homo erectus provided meaningful insights about the evolution of human ontogeny, life history, as well as cognition. The similarity between hominins is determined by testing three hypotheses (Leigh 105). With that being said, Mojokerto's absolute brain size is expected to be 0.5 - 1.5 year old H. sapiens (Leigh 105). The cranial

The general consensus today is that any genetic and anatomical similarities between anatomically modern humans and Neanderthals are coincidental and that the two species developed these similar traits independently

Evidence indicates Neanderthals and Modern humans shared a common African ancestor and split on the evolutionary tree between 500,000 to 200,000 years ago. Neanderthals developed in the cold and harsh environment of Europe and western Asia. With a lot of water locked up in the polar ice caps, Africa was experiencing a severe drought. This arid and dry environment is where modern human’s direct ancestor was living. These people’s bodies were a lot taller and weaker (to allow heat to escape) in comparison to the Neanderthals. This severe drought placed modern humans on the brink of extinction. However, when a species is dying out only the most inventive and resourceful survive, this causes the fitness of the remaining population to increase. In Europe the Neanderthals toughness allowed them to be very successful. In Africa the modern humans developed something the Neanderthals did not have, imagination. In Africa to survive it was necessary to think ahead and this allowed them to make the final step in becoming modern humans. Every previous human ancestor had been limited to the confines of their environment, but these ancestors eventually made their way out of Africa, and their imaginative behavior is illustrated in the drawings they left behind for others to find. After they left Africa they could have very well come into contact with the Neanderthals. Neanderthals became

Additionally, the phylogenetic trees were further supported through the measurements of jaw length and locations of the foramen magnum. First, the foramen magnum was observed to be more towards the middle of the skull for modern human (6.45cm) and Neanderthal (9.4cm) only which further supports the idea that these two species have very closely related to each other (Figure 13.1). The other six primates had their foramen magnum located more towards the back of the skull (Figure 13.1). Secondly, the jaw length of human and Neanderthal were similar with modern human having jaw length of 9.55cm and Neanderthal having a length of 10.5cm (Figure 13.1). On the other hand, a more similar jaw length was found in gorilla (15.7cm), Sumatran orangutan

Approximately 4 million years ago a wonderful evolutionary phenomenon was happening in Africa. Early hominids, man’s ancestors, were beginning a giant leap in their evolution. These hominids were moving out of the forest and beginning to walk upright, out on the open plains (Fagan, 98). This change from quadrupedalism was the most significant adaptation that ever happened to these early hominids. It caused many adaptations that make man what he is today. This process occurred in early hominids for many different reasons, each reason helping to perfect the upright walking posture. Bipedalism is thought to have occurred because of changes in environment, feeding habits, thermal regulation, and

The numbers for endocranial volume measured in centimeters for the mean in Homo Erectus were, 952.3, 1229.6 for Mid-Pleistocene and 1350 for the most recent humans. For the frontal arc, we really can not say that there is any similar measurement between the three because there are no measurements given to us for the recent humans. There are measurements for the parietal arc, and occipital arc both measured in millimeters. For the parietal arc measurements in Homo Erectus were 101.8, 114.8 for Mid-Pleistocene, and 125 for recent humans. In the occipital measurements for Homo Erectus, it was 108.6, in Mid-Pleistocene 122.8, and finally 111 for recent humans. One last similar measurement that I am going to mention is the frontal angle with 142.2 in Homo Erectus, 140.8 in Mid-Pleistocene, and lastly 129 in recent humans. In one last measurement that I am going to mention is the occipital angle measuring 104.2 for Homo Erecus,, 106.8 in the Mid-Pleistocene homonins, and 119 in recent humans. There were more measurements but the ones that showed the similarity between them were the ones that were put on here. The measurements clearly show that they are very close to the homonins in Mid-Pleistocene. We can also see that as evolution occurred, the skull increased in size due to the brain also

This racial discussion about cranial size has been going on for centuries, with the White brain and skull being larger than any other race. In recent years, studies have been done, especially by Rushton (1996), who has now changed the racial hierarchy. According to him the Mongoloid is now in the forefront, with Caucasoid next and lastly Negroid. Rushton

A human’s spine has an S shaped curve while the spines of apes have a C shaped curve.

Hominids with a brain absolutely and relatively larger than that of the australopithecines appeared about 2.3 million years ago. These hominids are classified in our own genus: Homo. The earliest species to appear was the Homo Habilis. It was the first of our ancestors to show a significant increase in brain size and also the first to be found associated with stone tools. These characteristics resulted in this species’ placement into the human genus, Homo.