ACROSS
2   Evolution in two or more species, such as predator and its prey or a parasite and its host, in which evolutionary changes in one species influence the evolution of the other species. 
4   Living underwater. 
5   The theory and practice of biological classification.
10   Australian-born South African anatomist and anthropologist (1893-1988). In 1924 he described a fossil skull collected near Taung in South Africa, naming it Australopithecus africanus. 
13   The process by which humans breed animals and cultivate crops to ensure that future generations have specific desirable characteristics. 
18   A two-footed, upright form of locomotion typical of hominins. 
20   Scientific study of the earliest stages of growth and development in organisms. 
21   A molecule made up of a sequence of amino acids. 
22   The physical or functional characteristics of an organism, produced by the interaction of genotype and environment during growth and development. 
23   An easy date. 

   DOWN
1   The species of humans that followed Homo habilis and preceded Homo sapiens 
3   An evolutionary mechanism that occurs when some individuals of a population are better able to adapt to their environment and, subsequently, produce more offspring. 
6   Heritable characteristic of an organism that improves its ability to survive and reproduce in its environment. 
7   Australopithecines and humans are… 
8   A simple measure of brain size but not necessarily of intelligence. 
9   Form of selection that tends to keep the form of a population constant. 
11   Members of any species of the genus Australopithecus. They lived during the Pliocene and early Pleistocene geological Epochs in Africa (i.e., ca. 4.2-1.4 million years ago). 
12   A scientist who uses fossil evidence to study early human ancestors. 
14   The process by which a similar character evolves independently in two species. 
15   Living in trees. 
16   The bones of the hip region. 
17   A sequence of nucleotides coding for a protein (or, in some cases, part of a protein); a unit of heredity. 
19   The study of ancestral relations among species, sometimes described as having a resemblance to ontogeny.

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