They show reduced sexual dimorphism, with males weighing between 42 and 60 Kg, while females weigh between 33 and 45 Kg. Based on our physical features, we can readily classify ourselves as mammals, primates, and hominoids. The hamadryas baboon shows some behavioural differences from the olive baboon. Aboitinz F (2001) Size and complexity of the brain in human evolution. The talon only includes one additional cusp, the hypocone (Hc), whereas the talonid may have up to three additional cusps: hypoconid (Hcd), hypoconulid (Hnd), entoconid (End). In fact, sexual dimorphism and its associated difference in sex-related roles vary depending on the size of the occupied territory and the abundance of food sources. The number of species of gorillas has varied. They show a short face and reduced mandibular branch, wide incisors, moderate canine size, dimorphic between sexes, short premolars, and low molar crowns with rounded cusps (bunodont). The occupy relatively small territories, where food items are dispersed, that include monogamous families of up to 4 offspring, giving birth a single new-born every 4-5 years. Hominin molar teeth show rounded cusps and a Y5 cusp pattern, whereas Papio and Theropithecus show 4 cusps arranged in parallel and joined by a bucco-lingual crest. The gleno-humeral joint in the arm also moves laterally and the humerus experiments a torsion that allows the ventral to dorsal swing of the arm, reducing the ability to brachiate but allowing the manipulation of objects in the ventral region of the body. They live in green forests and mainly eat leafs, fruit when available, and bark. During this period, brain communication capabilities need to be stimulated to properly complete development. Pan troglodytes is divided into four subspecies (Pan troglodytes troglodytes, Pan troglodytes verus, Pan troglodytes ellioti, Pan troglodytes schweinfurthii [eastern chimpanzee], Pan troglodytes marungensis [southeastern chimpanzee]), while P. paniscus has none. Non-human apes show strong temporal and masseter muscles, as well as great robusticity of the corresponding muscle attachments. This allows a more stable position of the vertebral column without strong muscle and ligament insertions and a lowering of the center of gravity. However, from a phylogenetic perspective, the models based on the chimpanzee are preferable for their evolutionary proximity to the hominines. The reduction of teeth number and dental complexity in the hominini is not highly significant. In contrast, if a chimpanzee stands up, its center of gravity is above the pelvic bone and the vertebral column is placed behind the body axis, which requires a continuous use of muscles in the pelvic area to compensate the inefficient equilibrium. Teeth constitute the hardest structures of the human skeleton and, thus, they are differentially preserved in the fossil record. The frontal lobe also includes the motor areas (areas 4, 6, 8, 43, 44) and Broca’s area (44-45) that connects the visual and auditory areas with the motor cortex. However, we now know that the first hominins attained bipedalism before having a large brain. The cercopithecoidea and hominoidea are considered sister taxa. Modern humans and modern apes evolved from a common ancestor. Grooming reinforces social interactions and relationships. But Lucy's feet weren't preserved. They form much smaller groups that share a significantly more open structure in which the groups may split or combine alternatively, mostly depending on environmental conditions and food availability. Therefore, these two muscles help to maintain the lateral equilibrium during the bipedal gait. The limbic lobe is related to emotional and affective processes, learning and memory (areas 25, 33, 24, 31, 23, 30, 26, 29, 27, 35, 28, 34). 3). The brain (cerebrum) is formed by an external area (the cortex) showing multiple imbrications that extend its overall surface.