Self-reinforcing feedback cycles organise the evolution of life on Earth. Here, I describe several types of evolutionary feedback cycles.

The evolution of abilities within a species

In any species, evolution does not act solely on genetics. Genes, physical capacities, senses such as hearing and sight, cognitive abilities, social behaviours like communication, and—even in some species—technological skills like tool making develop together as an integrated whole.

In early human ancestors, for example, genetic changes affecting hand bones and brain development reinforced one another. As grip strength and precision improved, individuals could manipulate stones more effectively; as tool use became more important, natural selection favoured enhanced brains with planning ability and fine motor control. Over time, these traits co-evolved, each amplifying the adaptive value of the others.

(The untold story of our remarkable hands and how they made us human: New Scientist: 17 Feb 2026)

Every species faces specific fitness demands shaped by its environment, and these demands often differ by sex and life stage. In lion populations, for instance, a mature lioness benefits from a collection of traits: effective maternal instincts, cooperative behaviour within the pride, hunting skill, physical endurance, and resistance to disease.

Evolution of the species proceeds through a self-reinforcing feedback process driven by natural selection:

The breeding population tends to have better-adapted individuals than the entire population.		The next generation tends to have better-adapted individuals than the previous generation.

In this virtuous cycle, (1) the breeding population tends to be better adapted to the environment because it is the population that has survived and reproduced. As these individuals pass on their traits, (2) the next generation’s overall population tends to be better adapted than the previous one, and this tends to result in (3) the next generation’s breeding population having better-adapted individuals, and then (4) the cycle repeats.

Across many generations, this iterative process produces cumulative adaptation. Because adaptations interact, natural selection gradually organises increasingly integrated and effective sets of abilities within a species.

The co-evolution of predators & their prey

Another feedback cycle that has contributed to the evolution of life on Earth is the co-evolution of predator and prey abilities, such as those of cheetahs and impala. Over many generations, this cycle can progressively increase the abilities of both populations.

Increased CHEETAH abilities.		Increased IMPALA abilities

In this symmetric amplifying feedback cycle, (1) an increase in the fitness of the cheetah population raises the selective pressure on impala, as the fittest impala survive more often. This tends to (2) increase the fitness of the impala population, which raises the selective pressure on cheetahs. This tends to (3) increase the fitness of the cheetah population and then (4) the cycle repeats.

Cooperative evolution: microbiome

Cooperation also plays a critical role in evolution. For example, the symbiotic relationships between:

• Bees and flowering plants
• Coral and algae
• Cleaner fish and sharks
• Humans and their gut microbes.

Consider the coevolution of humans and their gut microbes. Although humans and their gut microbes are distinct species, they form an integrated evolutionary unit, as they depend on each other for survival. The microbes survive into the next human generation through natural childbirth and breastfeeding. Humans benefit from the gut microbiome in many ways, but to keep this text simpler, I will focus only on the microbes that assist human digestion. This is organised by the same amplifying feedback cycle described above for the evolution of abilities within a single species.

The breeding population tends to have better-adapted individuals than the entire population.		The next generation tends to have better-adapted individuals than the previous generation.

In this situation, the “better adapted” includes:

• For humans, the ability to host the microbes by supplying them with nutrition and a stable environment, and
• For microbes, the ability to assist humans in digesting a wide range of foods. This ability would have been crucial during food shortages, which were often severe for early humans.

Specialisation in symbiotic evolution

In this symbiotic evolution between humans and their gut microbes, there was:

• the initial cooperative interaction between them,
• mutual benefit, which increased the reproductive success of both the humans and the microbes.
• modification of the environment for the microbes as the human gut became a honed niche for the microbes, and
• locked in cooperation, through the specialisation of both the humans and microbes.

The organisation of this specialisation is an example of a complementary system, another amplifying feedback cycle.

Microbes increase their ability to support human digestion of certain foods.		Humans reduce their ability to digest these foods in the absence of microbes and become increasingly dependent on the microbes.

This is a complementary relationship, an amplifying feedback cycle in which one party (the microbes) tend to increase a specific skill while the other party (humans) tend to lose the same skill.

Mutually reinforcing amplifying feedback cycles.

Here we have a group of amplifying feedback cycles, all mutually supporting one another in the evolution of life on Earth:

• The evolution within a species,
• The co-evolution of predators and prey,
• The co-evolution of symbiotic species, and
• The evolution of specialised cooperation between species.

Here, as in many other systems, amplifying feedback cycles interact and reinforce one another. They sometimes produce extraordinary outcomes, such as the intricate web of life on our planet. At other times, they organise destruction, e.g., global warming now threatens this very web of life in which humans have flourished.

Counselling Pages & References

The introduction to my counselling pages includes:

• Links to the other counselling pages, including those describing how this approach relates to other counselling practices and theories, see the top of the introduction page
• References for all the counselling pages, at the end of the introduction page.

Loaded: 19 Dec 2025: Updated 24 Feb 2026