User:Pancakes2022/Homo longi

Anatomy[edit]
H. longi is characterized by a low and long skull, receding forehead, extremely wide upper face, a large nasal opening equating to an enlarged nose (possibly an adaptation to the cold air), large and square eye sockets, inflated and thick brow ridges (supraorbital torus), flat cheekbones (zygomatic bone), a wide palate and large tooth sockets (equating to a large mouth), and a broad base of the skull. The Harbin skull measures 221.3 mm × 164.1 mm (8.7 in × 6.5 in) in maximum length x breadth, with a naso-occipital length of 212.9 mm (8.4 in), making it the longest archaic human skull to date. For comparison, the dimensions of a modern human skull average 176 mm × 145 mm (6.9 in × 5.7 in) for men and 171 mm × 140 mm (6.7 in × 5.5 in) for women. The Harbin skull also has the longest brow ridge at 145.7 mm (5.74 in). The Harbin skull is similar to the contemporaneous Dali skull (reconstruction above).

H. longi had a massive brain at roughly 1,420 cc, above the range of all known human species except modern humans and Neanderthals. Nonetheless, post-orbital constriction (constriction of the braincase just behind the eyes, equating to the frontal lobe, absent in modern humans) is more developed in H. longi than in Neanderthals, although not so much as in more-ancient human species. Overall, the braincase retains an array of archaic features, though the occipital bone at the back of the skull has a weakly-defined sagittal keel that lacks a protuberance at the midpoint, unlike most other archaic humans. Unlike the Dali and Hualong Cave skulls, there is no sagittal keel running across the midline. Unlike modern humans or Neanderthals, the parietal bones on the top of the head do not significantly expand or protrude.

Despite the face being so wide, it was rather flat (reduced mid-facial prognathism), and resembles the condition found in modern humans, the far more ancient H. antecessor, and other Middle Pleistocene Chinese specimens. Nonetheless, the tooth sockets for the incisors were angled outward (alveolar prognathism). The H. longi skull's mosaic morphology of archaic and derived traits converges with some of the earliest specimens assigned to H. sapiens from Africa, notably Rabat and Eliye Springs. Because the original describers judged the Harbin skull to be closely allied with the Xiahe mandible, they believed H. longi lacked a chin, like other archaic humans, but the specimen's lower jaw was not recovered. The only preserved tooth, the upper left second molar, is enormous, with a length x breadth (mesiodistal x labiolingual) of 13.6 mm × 16.6 mm (0.54 in × 0.65 in), comparable to the Denisovan molar recovered from Denisova Cave. The Harbin molar is oval-shaped and badly worn, nearly flat. In contrast, the average dimensions of a sample of 40 modern human male molars were 10.2 mm × 11.8 mm (0.40 in × 0.46 in).

The researchers believed the Harbin skull represents a male, judging by the extreme robustness and size of the skull, who was less than 50 years old, looking at the suture closures and the degree of tooth wearing. They speculated H. longi had perhaps medium-dark to medium-light skin, dark hair, and dark eye color based on reconstructed genetic sequences from Neanderthals, Denisovans, and early modern humans.

Habitat
Scientists believe the cranium came from a male individual living in a forested, floodplain environment as part of a small community. Similar to Homo sapiens, they hunted mammals and birds, gathered fruits and vegetables, and possibly caught fish. Due to the supposed large size of the Harbin individual as well as the location where the skull was found, researchers suggest H. longi may have been adapted for harsh environments, allowing them to survive and spread throughout Asia.