Living Things, Evolution and Human Origins: Key Concepts

Vital Functions of Living Beings

Living beings are characterized by their vital functions. All living beings have the capacity to exchange energy and matter with their environment and transform it through metabolic processes. Nutrition is a necessary function for every life activity.

Living beings replicate, forming copies of themselves. Reproduction, the duplication process, requires the transmission of genetic information. Living beings also receive information from the environment and respond to it. Relation with the environment is a fundamental function of all living beings.

Living beings are formed by molecules organized into cells.

The Process of Evolution

Evolution is a gradual process of change from one form to another. The impact that occurred in society has been one of the most discussed topics. Gradual evolution produces changes that are barely observable in a single generation.

The fossil record and the changes identified in it provide evidence of this process. Various theories consider evolutionary changes as the explanation for the observed diversity of species and their origin. Evolution considers that all species originated from others. Consequently, each species has an ancestor, and it is possible to establish hypotheses about these relationships.

Lamarck's Theory

Jean-Baptiste de Monet, Chevalier de Lamarck, explained that changes or transformations in living beings produced new species and led to the emergence of closely related species. However, they did not contain the first authentic evolutionary theory explaining the origin of all species.

Lamarck proposed that simple organisms arose frequently through spontaneous generation. Internal forces within living beings drove them toward greater complexity. Changes in the environment forced individuals to use certain organs more, or less, in response to their needs, and these acquired characteristics were transmitted to their descendants.

Lamarck's ideas were attractive because they proposed a way for living beings to gradually improve and adapt over the generations. However, critics pointed out several reasons why the theory fails:

1. No evidence has demonstrated that acquired characteristics are inherited.
2. In light of genetic knowledge, it is not possible to prove the inheritance of acquired traits.

Darwin's Theory of Natural Selection

Darwin's theory coincides with Lamarck's in some arguments: in a changing world, living beings also change; evolution is a gradual and continuous process; and organisms that share similarities are related. However, Darwin proposed that evolutionary change occurs through natural selection.

Darwin's reasoning is based on the following observations: populations of living beings present individual variants, these differences are heritable, and, despite the potential for population growth, the number of individuals remains more or less constant. Individuals with favorable variations survive and reproduce more, passing those traits to the next generation.

Human Origins

Hominids belong to a group of primates whose origin lies in Africa, dating back about 7 million years. Humans are hominids, but not all hominids are humans. Hominid characteristics include:

• Always moving in an upright, bipedal position.
• This posture determines the location of the foramen magnum at the base of the skull, and the spinal column passes through the vertebral column.
• The palate is shaped like a rounded arch, with small teeth.
• The cranium houses a large brain. This increase in brain size is related to a diet rich in energy-dense content.

Main hominid species include Ardipithecus ramidus, one of the oldest known hominids. Australopithecus anamensis had an appearance similar to that of hominids. Australopithecus afarensis had a very prominent face. Later hominids include Paranthropus, Africanus, and the new species Homo garbi.

Neanderthals appeared in Europe about 300,000 years ago and disappeared around 28,000 years ago. Their range extended to Asia. They had an average height of 1.65 m, well-developed musculature, and a primitive cranial structure, with dentition similar to ours. Some researchers consider Homo heidelbergensis to be the common African ancestor of our species.

Homo sapiens appeared in Africa about 160,000 years ago. Modern humans occupied the entire planet, replacing other hominid species that had disappeared. The Cro-Magnon people were early modern Homo sapiens.