"The idea that in evolution the strongest, largest, and fastest always wins is one of the most common misconceptions about life on Earth.
Charles Darwin warned against this interpretation of his teachings.
However, he included Herbert Spencer's formula of "survival of the fittest" in a later edition of his standard work—and thus paved the way for Social Darwinist claims of all degrees.
The fact that this fitness, in an evolutionary sense, is not synonymous with muscular strength and physical endurance, nor with intelligence, but rather represents successful adaptation to the respective living conditions, has been frequently overlooked since then. Selfishness, competition, the oppression, or even extermination of the weaker have been presented as the most important driving forces of evolution, which are also inherent in human nature.
With his book "Survival of the Nettest," Dirk Brockmann, physicist, mathematician, research biologist, and founding director of the "Synergy of Systems" Center at the Technical University of Dresden, presents an original counter-proposal to the doctrine of omnipresent evolutionary competition.
He does so not in the form of an attack or a reckoning, but rather as a vivid narrative depiction of how much life on Earth is characterized by cooperation—from genes to the emergence of new life forms to entire ecosystems.
"We have never been individuals."
The author repeatedly quotes a maxim by the evolutionary and microbiologist Lynn Margulis, who died in 2011: "Life conquered the globe not through struggle, but through networking."
One of Margulis's achievements was helping to bring about the breakthrough of the so-called "endosymbiont hypothesis": The cells that make up not only our bodies, but the bodies of all multicellular organisms, are the result of a fusion of at least two, possibly three fundamentally different, yet complementary single-celled organisms 2.2 billion years ago, explains Brockmann. Thus, symbiosis, rather than competition, was at the very beginning of our own evolution.
Other key events in life also occurred in symbioses, such as the emergence of plants on land – as lichens in interaction with fungi.
Dirk Brockmann: "Survival of the Nettest." How nature shapes our world through cooperation.
Dirk Brockmann: "Survival of the Nettest." How nature shapes our world through cooperation. dtv
Brockmann uses a rather well-known example to demonstrate how influential the basic principle of cooperation is: the microbiome in the human gut and on our mucous membranes. The thousands of species of bacteria and archaea with which we share our bodies together amount to millions of genes that function as blueprints for proteins. The human genome, in contrast, is estimated at only about 23,000 genes.
"Genetically and thus biochemically, we are significantly more bacteria than humans," Brockmann points out, quoting a team of evolutionary biologists who stated: "We have never been individuals." In fact, almost all living things are "holobionts," or communities of different species [1].
A share in the enormous biodiversity of the insect world
What follows is a journey across the globe that is as wild as it is fascinating: to a sea slug that performs photosynthesis after a retrovirus has given it the necessary genetic makeup, to frog embryos that form alliances with single-celled algae, to dwarf squids that, in conjunction with bacteria, make themselves invisible to predators. How exactly these bacteria manage to become part of the squid's body is truly astonishing. This also applies to other examples, such as the pear-shaped structure composed of five different microorganisms that enables Australian Darwin termites to digest cellulose.” [2]
1. A holobiont is a unit of biological organization consisting of a host organism and the diverse community of microorganisms (microbiota) that live in or on it, functioning together as a discrete ecological unit. These microbial communities, which can include bacteria, archaea, fungi, and viruses, are crucial for the holobiont's health, development, and evolution. The term "hologenome" refers to the collective genomes of both the host and its associated microbiota.
Key Aspects of Holobionts:
Host Organism: Typically a multicellular eukaryote, like humans, animals, or plants.
Microbiota: The diverse community of microorganisms, including bacteria, archaea, fungi, and viruses, that inhabit the host.
Hologenome: The combined genetic material of the host and its microbiota.
Symbiotic Relationship: The host and its microbiota form a symbiotic relationship, with each influencing the other's biology and evolution.
Ecological Unit: Holobionts function as a single, integrated ecological unit, with interactions between the host and its microbiota impacting the overall health and fitness of the system.
Examples of Holobionts:
Humans:
Our bodies are inhabited by trillions of microorganisms that play vital roles in digestion, immunity, and overall health.
Research shows that endogenous retroviruses (ERVs) play a significant role in protecting the developing embryo from the maternal immune system in mammals, according to the National Institutes of Health (NIH). This involves several mechanisms:
Immune modulation: ERV-derived proteins in the placenta may help suppress the maternal immune response locally, enabling deeper invasion of the placenta and potentially prolonging gestation time.
Cell-cell fusion: Syncytins, retroviral envelope proteins expressed in the placenta, facilitate the formation of a multinucleate barrier, the syncytiotrophoblast, which separates maternal and fetal bloodstreams, protecting the fetus from immune attack and enabling nutrient exchange.
Protection against exogenous viruses: Placental expression of replication-incompetent ERVs can protect the host from infection by related exogenous viruses.
This evolutionary interplay between retroviruses and host defenses likely contributed to the remarkable diversity of mammalian placentas and genomic imprinting. While ERVs can sometimes be pathogenic, their integration into the genome and subsequent "domestication" by the host has provided significant advantages for mammalian reproduction.
Corals:
These marine invertebrates rely on symbiotic algae for energy and rely on their microbial communities for nutrient cycling and protection.
Plants:
Plants have complex relationships with fungi and bacteria in their roots (mycorrhizae) and other tissues, which are crucial for nutrient uptake and disease resistance.
Research on mycorrhizal networks (also called the "wood wide web") has uncovered a fascinating phenomenon where fungi form symbiotic relationships with plant roots, creating vast underground networks. These networks facilitate the exchange of resources, including nutrients and carbon, between plants, even between those of different species, showing that idea of evolution as a competition between species is too simplistic.
The idea that mature trees, sometimes referred to as "mother trees," support the growth of smaller or weaker seedlings by transferring resources through these fungal networks is known as the mother tree hypothesis. While compelling and gaining significant popular attention, the hypothesis remains controversial within the scientific community.
Here's a closer look at the key points:
How do fungi and plants benefit?
Mycorrhizal fungi and plants engage in a mutualistic relationship where the fungi enhance the plant's ability to absorb water and nutrients (like phosphorus and nitrogen) from the soil, in exchange for carbohydrates (sugars produced through photosynthesis) from the plant.
What is the mother tree hypothesis?
The hypothesis suggests that older, established trees, or "mother trees," can share resources with nearby seedlings, potentially enhancing their growth and survival. This idea gained popularity through studies showing the transfer of carbon isotopes between connected trees, according to TreePeople.
Debates and complexities
Despite the compelling nature of the mother tree hypothesis, several studies have raised questions and presented conflicting evidence. Some arguments include:
Evidence is inconclusive or absent in some cases: Recent reviews suggest that the evidence for substantial and beneficial carbon transfer from mother trees to seedlings through Common Mycorrhizal Networks (CMNs) is inconsistent.
The evolutionary rationale is unclear: Critics question why fungi would act as simple conduits for altruistic sharing between trees, as it challenges the principle of mutualism where both partners aim to maximize their benefits.
Explanation: Both plants and fungi survive stresses of life in forest better than in open spaces, where the soil is easily washed of during a strong storm.
Methodological challenges: Measuring inter-tree resource transfer accurately is difficult due to factors like microbial activity, soil diffusion, and the potential for observed effects to be overstated or confounded by alternative processes.
Potential for negative impacts: Some research indicates that competition for resources, even through these fungal networks, can be a dominant factor, and that seedling growth might be inhibited near mature trees in certain situations (if the forest is too dense around them).
Interpreting resource transfer: Identifying whether detected labeled carbon isotopes in recipient seedlings represent an actual transfer to the plant, or remain within the fungal tissue and are not directly beneficial, is an ongoing area of discussion, according to Wiley.
In conclusion, while the idea of mother trees nurturing offspring of different species through fungal networks is captivating, it's important to recognize the complexities and ongoing scientific debate surrounding the hypothesis. Mycorrhizal networks undoubtedly play a vital role in forest ecosystems, but further research is necessary to fully understand the mechanisms, extent, and ecological implications of inter-plant resource transfer through these fungal connections.
Evolutionary Significance:
The holobiont concept highlights the importance of microbial communities in the evolution of their host organisms. The hologenome, with its vast genetic diversity, provides a rich source of variation for natural selection to act upon, potentially driving evolutionary change in both the host and its associated microbiota.
2. Genetisch sind wir deutlich mehr Bakterie als Mensch. Frankfurter Allgemeine Zeitung. Jul 10, 2025; (157) Von Christian Schwägerl.
