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Earliest development of bilateral symmetry, mesoderm, head (anterior cephalization) and various gut muscles (and thus peristalsis) and, in the Nephrozoa, nephridia (kidney precursors), coelom (or maybe pseudocoelom), distinct mouth and anus (evolution of through-gut), and possibly even nerve cords and blood vessels. [8]
The earliest evidence for life on Earth includes: 3.8 billion-year-old biogenic hematite in a banded iron formation of the Nuvvuagittuq Greenstone Belt in Canada; [30] graphite in 3.7 billion-year-old metasedimentary rocks in western Greenland; [31] and microbial mat fossils in 3.48 billion-year-old sandstone in Western Australia.
E-C theory holds that new bio-psycho-social coping systems emerge within humans in response to the interplay of external life conditions or existential problems with internal neurobiology. It is this interaction, which cycles between what Graves referred to as "express self" and "sacrifice self" systems, which is the core of the theory [23]
In biology, evolution is the process of change in all forms of life over generations, and evolutionary biology is the study of how evolution occurs. Biological populations evolve through genetic changes that correspond to changes in the organisms' observable traits.
This change in gait saw a lengthening of the legs proportionately when compared to the length of the arms, which were shortened through the removal of the need for brachiation. Another change is the shape of the big toe. Recent studies suggest that australopithecines still lived part of the time in trees as a result of maintaining a grasping ...
Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development [1]), usually from the time of fertilization of the egg to adult. The term can also be used to refer to the study of the entirety of an organism's lifespan.
The word evolution (from the Latin evolutio, meaning "to unroll like a scroll") was initially used to refer to embryological development; its first use in relation to development of species came in 1762, when Charles Bonnet used it for his concept of "pre-formation," in which females carried a miniature form of all future generations. The term ...
A fetus is a stage in the human development considered to begin nine weeks after fertilization. [4] [5] In biological terms, however, prenatal development is a continuum, with many defining features distinguishing an embryo from a fetus. A fetus is also characterized by the presence of all the major body organs, though they will not yet be ...