Humans {Homo} {human} are vertebrates, mammals, and primates and share their fundamental behaviors.
evolution
Humans evolved from australopithecines. Strong sexual selection, complex social lives, changing environments, cultural effects, social contacts, increased population density, agriculture, food surpluses, and wars emphasize aggression, fitness, and intelligence. Humans evolved faster than apes. Humans evolved through pedomorphism, accounting for greater brain size, because children have relatively bigger brains.
evolution: environment
Early humans had direct competition with similar species and had predators.
development
Human life span is as expected for great apes with human size and brain.
behavior: hand
Hands have opposing thumbs and many available grips. Humans can gesture.
behavior: walking
Humans walk upright on strong legs. Upright walking requires mechanisms for balance, allows farther vision and greater lateral vision, requires learning gait, allows wider territory and means of sharing territory, and allows hand, foot, arm, and leg differentiation.
behavior: society
Humans live in organized groups. They have faces and know facial expression meaning. They perceive others' needs and desires. They know action effects on others. They react to others' behaviors and communications. They can have rapport. They can influence. They kiss.
behavior: language
Human language probably developed from graded primate vocalizations. Humans can pronounce 40 phonemes. They use voice modulation. They express feelings. Speech depends on upright posture, which allows tongue-position shifts and pharyngeal-tract lengthening. Humans use symbolic thought and language to plan and form strategies. Memories allow using and transmitting past knowledge. Humans have music.
senses
Humans use sight as dominant sense.
brain
In evolving to humans, supragranular layer became upper three cortical layers, middle layer thickened, subgranular layer divided into lower two layers, and secondary and tertiary sulci had increased associational areas.
handedness
Right-handedness first appeared in Lower Old Stone Age, when tool making became common. Starting 300,000 years ago, humans probably had cerebral dominance, because skulls are asymmetric and people inherit brain and skull shape. Human skulls mold to brains. Right-handers typically support and orient objects in left hand, without using visual feedback, and perform fine movements with right fingers, using visual feedback. Most people use right hand for gesticulation.
handedness: abilities
Performance by right-handers and left-handers is equal on all tasks. No special ability or disability distinguishes left-handers.
handedness: factors
Handedness inherits. Social pressures or early experience, especially with objects designed for right-handers, affects handedness. Brain damage before or after birth can shift cerebral dominance or prevent hemispheric specialization. Subnormal and epileptic people have more left-handedness.
handedness: anatomy
In right-handers, left cerebral hemisphere has sense and motor connections to both body sides, and right hemisphere connects to only one side. In left-handers, cerebral lateralization is less. In right-handers, left side has fewer skills, poorer timing and coordination, more variability, and more frequent and slower corrections.
handedness: ratio
Left-handers are 4% to 36% of people in different races and cultures.
handedness: mammals
Mammals besides humans show paw preferences but equally to left or right.
Biological Sciences>Zoology>Kinds>Hominin
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Date Modified: 2022.0224