Born in Africa_ The Quest for the Origins of Human Life - Martin Meredith [89]
Chromosomes: Structural elements found in the nucleus of a cell and containing the major part of hereditary material (the genes). Chromosomes are composed of DNA and proteins.
Competitive exclusion principle: The theory that two species cannot exist at the same locality if they have identical ecological requirements.
Continental drift: The movement of continents in geological time due to the drift of the plates of the earth’s crust caused by plate tectonics.
Derived character: A new trait developed in a more recent ancestor and retained by descendants but absent in older ancestral stock, which shows a primitive version of the same trait. (See Primitive character.)
DNA: Deoxyribonucleic acid, the molecule carrying hereditary genetic information in all living cells. A DNA molecule consists of a pair of nucleotide chains twisted together in an elegant spiral: the ‘double helix’.
Early Stone Age: The first part of the Stone Age, usually applied to Africa, starting around 2.5 million years ago and spanning the Oldowan and Acheulean lithics industries. The same period in Eurasia is referred to as the Lower Palaeolithic.
Fluorine absorption dating: A relative dating technique that determines the duration of time an object has been lying in the soil by measuring the amount of fluorine it has absorbed.
Fossil: The remains or impression of a prehistoric plant or animal that has become hardened into rock.
Hand-axe: A pointed, teardrop-shaped bifacial stone tool most commonly used for butchery purposes.
Haplogroup: A group of people who share a set of genetic markers and therefore share an ancestor. In human genetics, the haplogroups most commonly studied are Y-chromosome haplogroups and mitochondrial-DNA haplogroups, both of which can be used to define genetic populations
Hominid: A term commonly used throughout the period this book covers to refer to all human and pre-human species that ever evolved. In strict taxonomic terms, however, chimpanzees and gorillas are also hominids. Some modern researchers therefore prefer to use the term ‘hominin’ to describe human and pre-human lineages, thereby excluding chimpanzees and gorillas from the definition. This book keeps to the traditional meaning of hominids. This includes all of the Homo species (such as Homo sapiens, Homo ergaster, Homo habilis and Homo rudolfensis); all of the australopithecines (such as Australopithecus africanus and Australopithecus afarensis); and other human ancestors such as Ardipithecus.
Hominin: A term used by modern researchers to describe human and pre-human lineages that excludes chimpanzees and gorillas.
Late Stone Age: The third stage of Africa’s Stone Age, starting 50,000 years ago, roughly contemporaneous with Europe’s Upper Palaeolithic.
Locum: A doctor standing in for another who is temporarily absent.
Matrix: In palaeontology, the mass of rock or other material in which a fossil is embedded.
Middle Stone Age: The second stage of the Stone Age, applied to Africa, starting about 300,000 years ago, which sees the appearance of more advanced tool-making technologies. The same period in Eurasia is referred to as Middle Palaeolithic.
Miocene: The epoch from 23.3 million to 5.2 million years ago, a period when the first apes appeared and when the common ancestor of humans and chimpanzees split.
Mitochondria: Tiny structures that lie outside the nucleus of a cell and exist as separate organelles with their own DNA. Mitochondrial DNA (mtDNA) is inherited solely through the female line. It is therefore a useful tool for charting population histories.
Molecular clock: The clocklike regularity of the change of a molecule or a whole genotype over geological time.
Morphology: The study of animal structure or form.
Multiregional evolution hypothesis: The hypothesis that modern humans evolved in near concert in different parts of the Old World.
Mutation: An inheritable alteration in genetic material, most commonly an error of replication during cell division.
Natural selection: The