Born in Africa

Absolute dating: The process of determining an approximate age for an archaeological or palaeontological site or artefact, usually based on tests of the physical or chemical properties of materials or other items. Methods include carbon dating and potassium-argon dating. Absolute dating techniques contrast with relative dating techniques, such as stratigraphy.

Acheulean: The name given to an archaeological industry of stone tool manufacture, characterised by large bifaces, including hand-axes. It originated in Africa about 1.5 million years ago, spread to parts of western Asia and Europe and continued in use until about 200,000 years ago.

Adaptive radiation: The rapid diversification of species that occurs after an initial evolutionary innovation.

Archaeology: The study of human behaviour and artefacts in history and prehistory.

Ardipithecus: An early hominid genus found in Ethiopia that lived from about 5.8 million to about 4.4 million years ago.

Australopithecines: A subfamily (Australopithecinae) consisting of a single genus (Australopithecus) of extinct hominids that lived from about 4.2 million years ago until about 1 million years ago.

Basalt: A dark, fine-grained volcanic rock.

Biface: A rock core that is flaked on both sides to form a sharp edge around its periphery, such as a hand-axe.

Bipedality: Upright walking on two feet.

Biota: The combined fauna and flora of an area.

Breccia: Rock consisting of angular fragments cemented by finer chalky material. (Italian for ‘broken things’.)

Carbon-14 dating: An absolute dating method, based on the decay of the radioactive isotope of carbon, carbon-14.

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 process by which in every generation individuals of lesser fitness are removed from the population.

Oldowan: An Early Stone Age industry, first described from Olduvai Gorge, lasting from about 2.6 million to about 1 million years ago. It is characterised by scrapers made from flakes split by hammerstones and by crude choppers made from cobbles—hence the name ‘pebble tools’.

Palaeoanthropology: The study of the physical and behavioural aspects of humans in prehistory.

Palaeolithic Age: A prehistoric era in Eurasia divided into three main parts—Lower Palaeolithic, Middle Palaeolithic and Upper Palaeolithic—that are roughly contemporaneous with the three stages of Africa’s Stone Age.

Palaeomagnetic dating: A geological technique that dates rock based on the occurrence of polar reversals when the magnetic pole moves to the opposite end of the earth. Such reversals have occurred at regular intervals of hundreds of thousands of years throughout the history of the earth.

Palaeontology: The study of fossils and biology of extinct organisms.

Palynology: The study of contemporary and fossil palynomorphs, such as pollen.

Phyletic gradualism: A mode of evolution characterised by gradual change within a lineage.

Phylogeny: The reconstruction of evolutionary relationships between groups and species, primarily concerned with branching events, usually shown as a branching diagram or phylogenetic tree.

Plate tectonics: The study of the earth’s crustal structures, such as continental plates, and the forces that cause them to change shape and move relative to one another.

Pleistocene: The epoch from 1.64 million to about 10,000 years ago, a period which included the Ice Ages and the evolution of the first members of the genus Homo in Africa.

Pliocene: The epoch from 5.2 million to 1.64 million years ago when the first hominids evolved in Africa.

Pongidae: The family of great apes that includes chimpanzees, gorillas and orang-utans and their ancestors.

Potassium-argon dating: A radiometric dating method based on measurement of the product of the radioactive decay of an isotope of potassium into argon.

Primitive character: A character that was present in a common ancestor of a group and is therefore shared by all members of that group. (See Derived character.)

Proteins: Large molecules that consist of a long chain of amino acids.

Punctuated equilibrium: A mode of evolution characterised by periods of stasis interspersed with brief episodes of rapid change.

Radiometric dating: Clocklike dating methods based on the measurement of the constant rate of decay of naturally occurring radioactive materials.

Relative dating: Techniques that provide information about a site by referring to what is known at other sites or other sources of information, such as faunal correlation. (See Absolute dating.)