Everyone knows that biology is complicated – even just understanding all of the different branches of biology is an endeavour of its own.

Jump straight to diagram

There was a day when someone could call themselves a biologist– and be no more specific than that. In fact, before then you could be a general scientist – for example, Robert Hooke, who in 1665 the was the first person to identify biological cells and so I’m going to call a biologist, was also a physicist (discovered the proportional relationship of the extension of a spring and almost beat Newton to the law of universal gravitation) and as an added bonus was an architect involved in the reconstruction after the 1666 Great Fire of London.

The term biology was coined around the turn of the 18th century, its areas of research previously being under the grand scope of “natural history” which had also included minerology and astronomy.

As the knowledge of the biological world expanded, individual areas were given their own labels. Nowadays, a typical university will offer several specialist undergraduate courses, such as human biology and biochemistry, as well as an overall biological sciences degree. And this then splinters into dozens of more specific topics for postgraduate study.

To show how the field of biology can be categorised in two axis (organism type, scale) I’ve created a Venn diagram-like montage illustration. I’ve only included biology disciplines with “bio” in the name – and not even all of those to keep the diagram readable. An even longer list would be related fields without “bio” in the name, such as anatomy, genetics, physiology, and medicine. And of course, the sub-topics of biology don’t branch out like a tree – they all overlap too, so that botany and cell biology overlap as plant cell biology.

Branches of Biology Diagram

Branches of Biology Definitions

To provide a bit more background, here are some basic definitions of the branches of biology shown in the diagram as well as few others for good measure.

Astrobiology‎ (or exobiology)

The study of life, and its origins, in the universe. Using a combination of biochemistry, biophysics and geobiology (and more) astrobiology looks at conditions and astronomical processes that give rise to habitable environments for life.
More about astrobiology on Wikipedia.

Biochemistry

Underlying all biological processes are chemical processes, so this branch of biology studies chemical processes relating to living organisms and particularly their components such as organelles, proteins, and lipids.
More about biochemistry on Wikipedia.

Biogerontology

Looking at the biological basis of ageing and age-related diseases, biogerontology examines mechanisms of biological aging and how much damage needs to be repaired or removed in order to regain health and functionality.

Obviously, this sub-field of biology is of particular interest to life extensionists who are trying to slow, prevent, and even reverse aging.
More about biogerontology on Wikipedia.

Bioinformatics

To better understand biology, we need to capture and interpret as much biological data as possible. This is where bioinformatics comes in, using methods and tools from computer science (such as image and signal processing) to store and analysis this vast amount of raw biological data (such as DNA and amino acid sequences).

See also: systems biology
More about bioinformatics on Wikipedia.

Biology

The scientific study of the natural processes of living organisms – i.e. life. Encompassing all types of life and its many levels of organisation from chemical reactions to evolution.
More about biology on Wikipedia.

Biomedicine

Branch of medical science based on the application of the principles of biology to clinical practice. Uses evidence-based treatment supported by an understanding of anatomy and physiology.
More about biomedicine on Wikipedia.

Biophysics

Biophysics uses the principles and methods of physics to understand biological systems, from intramolecular length scales up to the population level.
More about biophysics on Wikipedia.

Biotechnology

Rather than using technology to understand biology, biotechnology uses our understanding of biology to develop new technology or products from living organisms, for example, with genetic engineering.
More about biotechnology  on Wikipedia.

Botany

The branch of biology interested in plant life. Also known as plant biology, or phytology. It includes their classification, structure, properties, and biochemical processes.
More about botany on Wikipedia.

Cell Biology (cytology)

The study of cell structure and function, to understand how prokaryotic and eukaryotic cells work at a molecular level and within the tissues and organisms that they compose.
More about cell biology on Wikipedia.

Chronobiology

The study of biological rhythms and timing processes in living organisms which help them perform over cycles such as the 24-hour day (circadian rhythm) and longer (infradian rhythms).
More about chronobiology on Wikipedia.

Developmental Biology

Field of biology that studies how multicellular organisms (animals and plants) grow and develop, examining a variety of interacting processes that generate their shape, size, and structural features, including how the right types of cell form in the right place.
More about developmental biology on Wikipedia.

Evolutionary Biology

Subdiscipline of biology concerned with the origin of life, evolutionary processes (e.g. natural selection) and the diversification and adaptation of life forms and how they change over time.

More about evolutionary biology on Wikipedia.

Geobiology‎

A relatively new field of biology studying the interaction, in both directions, between the geosphere and biosphere – both the emergence of life (over geologic time) and how microorganisms impact the chemical and physical environment.
More about geobiology on Wikipedia.

Human Biology

A broad and deep interdisciplinary area of biology studying the human body and the interaction between humans and their environment. Its overlapping fields include physiology, anatomy, nutrition, growth and aging, genetics, epidemiology and population biology.
More about human biology on Wikipedia.

Microbiology

Branch of biology dealing with microorganism (i.e. microscopic forms of life which are not visible to the human eye) such a bacteria, viruses, fungi and protozoa (single-celled eukaryotes).
More about microbiology on Wikipedia.

Molecular Biology

Molecular biology studies the composition and interactions of cellular molecules inside and between cells. Of particular interest are the nucleic acids and proteins involved in DNA transcription and translation.
More about molecular biology on Wikipedia.

Structural Biology

Branch of biology studying structure, function and interactions of biological macromolecules (especially proteins and nucleic acids). Areas of interest overlap with molecular biology, biochemistry, and biophysics.
More about structural biology on Wikipedia.

Systems Biology

To help understand complex biological systems, systems biology uses computational and mathematical analysis to model biological processes from individual cells to whole ecosystems.
See also: Bioinformatics
More about systems biology on Wikipedia.

Zoology

The branch of biology involved in the scientific study of the animal kingdom (including marine biology). As with biology generally, it includes the their classification, structure, evolution and ecosystems.
More about zoology (animal biology) on Wikipedia.

Image credits

Illustration composed of the following images:

Astrobiology - Rene Tittmann (Pixabay)
Biochemistry - Shafin Al Asad Protic (Pixabay)
Biogerontology - Free-Photos (Pixabay)
Biology - Free-Photos (Pixabay)
Biophysics – Indolences (Wikimedia Commons)
Biotechnology - Gerd Altmann (Pixabay)
Botany - Wolfgang Eckert (Pixabay)
Cell biology – Sieglinde Sterbling (Pixabay)
Geobiology - Bernard Gagnon (Wikimedia Commons)
Human biology - Keith Johnston (Pixabay)
Microbiology - TBC
Molecular biology – WikimediaImages (Pixabay)
Systems biology - Gerd Altmann (Pixabay)
Zoology - TBC