↣ Evidence of evolution

Evolutinary theories are based on scientifc evidence. This is why nowadays evolution is considered to be a proven fact.

3.1 Anatomical and morphological evidence

By comparing the anatomy of living things with those found in fossils, organs can be classified into three different groups, which support the theory of evolution.

3.2 Fossil evolution

Fossils show organisms that existed in the past and that are different from present-day organisms, so species do change over time. Some fossils from different eras, but whose species are related, have been found, When observing these fossils, we can see slow but progressive transformations, which is valuable proof of evolution. They allow us to study the evolutionary lineage of a particular living thing.

Fossils support the ideas behind evolutionary theories, as they prove there were living things in the past that had similar characteristics to different present-day groups of living things. Fossils are considered to be evolutionary links (between a primitive group and a more evolved one).

Some organisms have not changed over time, or have changed very little. These organisms are known as living fossils. They are very interesting creatures as they provide us with information that fossils cannot give us. Their primitive characteristics are another type of evidence that supports evolutionary theories.

3.3 Embryologycal evidence

In 1866, Ernst Haeckel explained his biogenetic law for the first time. The law. states that embryonic development (ontogeny) is a summary of evolution (phylogeny). When the embryos of different species are similar, there is an evolutionary relationship between them. The closer the relationship between two species is, the greater the similarities between their embryos.

3.4 Biogeographical evidence

The geographical distribution of animal and plant species can be explained according to theories of evolution. As time passed, isolated groups of animals evolved in different ways, creating new species.

3.5 Molecular evidence

The study of molecules found in living things reveals that the higher the molecular similarities between two groups of organisms, the closer their evolutionary relationship.

In the case of some molecules, such as chlorophyll (found in every single green plant) or haemoglobin (found in vertebrates' blood), it is very clear that there is a common evolutionary origin.

 As you know, living things have two types of molecules (proteins and DNA). These molecules are made up of smaller molecules that join together (amino acids and nucleotides respectively). The smaller molecules join in specific sequences, different in each organism. When we compare the sequences of different species, we can accurately establish how closely related they are from an evolutionary point of view.

3.6 Other evidence

Coevolution is the process through which two species mutually influence each othe during their evolution, Coevolution can be observed in many different examples:

↦ Mutualism: an interaction between two species in which they both benefit, Plant and insects depend on each other. Flowers produce nectar that insects eat, whilkt insects help in the pollination process.

↦ Parasitism: when a particular species benefits from another one. There are similar parasites found in species that are closely related.

 For example, pelican and geese share the same type of lice, whereas lice found on cranes are different, as cranes are not as closely related.

↦ Mimesis: capacity of some species to look like other species or the environment in order to ensure their survival. Evolution has favoured the species that developed warning signals against predators. This way, they remind them that they are poisonous. The pattern found in wasps, bees and some spiders (alternating yellow and black bands) is an example of mimesis.