Since the biosphere started to become relevant on Earth’s surface, around 575.000.000 years ago, diverse microorganisms, macroorganisms, plants, and animals have all been shaped by the environmental conditions at Earth’s surface in a given space and time through their metabolism.
Metabolism, in turn, is responsible for fabricating the genes that shape them throughout the years, with distinct species developing similar features throughout the same period of time. The intertwined relationship between a given environment and its inhabitant organisms is what the scattered fossil record humans have so far portrays.
To illustrate, somewhere between 200,000,000 and 145,000,000 years ago, according to the fossil record, wings (as they are today) appeared together in both birds and insects.
The same pattern appeared again 55.000.000 years ago. Spanning some 200.000 years, planet Earth’s surface temperatures hit a threshold of warm climate, with surface temperatures ranging from 5 to 8 degrees Celsius hotter than the long-term average inferred from geological records.
Curiously, not all of the globe experienced the same warm temperatures. Data show that the poles managed to get warmer while the tropics maintained their temperature (a combination of global climate dynamics associated with Earth’s mantle activity can explain this phenomenon), with tropical forests occurring on all landmasses throughout Earth’s surface.
In response to such a scenario, some terrestrial mammals adapted to life in trees started to appear in fossil records. These mammals, called primates, have a set of distinct characteristics to make use of the trees, such as mobile shoulder girdles (that allow them to climb trees), opposable thumbs (to hold branches better), and the presence of nails (to maintain a tight grip and perform fine motor movements).
Continuing along the same line of thinking, by 50.000.000 years ago, there was a considerable rise in sea levels with increasing availability of marine organic matter and a decrease in terrestrial organic matter. Under such environmental pressures, terrestrial mammals transitioned to aquatic life, with whales and dolphins appearing in the fossil record around this time. In 2026, several studies confirmed these scenarios, including one from June 2026, which described a whale fossil whose teeth show an intermediate stage between the grinding teeth of land-dwelling ancestors and the sharper, slicing teeth of early aquatic predators.
Last but not least, by 37.000.000 years ago, large lakes were present on Earth’s surface, making the largest terrestrial mammal—elephants—transition into a semi-aquatic lifestyle, explaining their furless skin, which humans can witness today.
In this way, according to empirical evidence, organisms simply respond and adapt to their environmental conditions through their metabolism, primarily focused on their own reproduction and survival.
In the case that the organisms’ environmental conditions change to the point that it affects their metabolism, their metabolisms will change, and consequently, their genetic composition also changes, which may or may not give rise to a new species over the years.
Demystifying the relationship between environment and metabolism is not just an academic exercise. It is the foundation for understanding how the environments are shaping life today.
The same forces that gave primates their opposable thumbs, whales their aquatic bodies, and elephants their furless skin are still at work. Humans are not exempt.
The question is not whether life is being shaped. The question is whether humans will pay attention to what is being built.
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