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What is Impossible in Evolution?

Be Smart・2 minutes read

Certain traits are absent in nature due to physical limitations, like animals not having wheels as body parts. Environmental factors influence adaptations, as seen in the disappearance of wheeled vehicles in favor of camels in some regions.

Insights

  • Evolutionary constraints prevent the development of traits like wings for humans, as each stage of evolution must be advantageous, showcasing how the fitness landscape concept influences trait evolution.
  • The concept of "forbidden phenotypes" in evolution, such as animals with wheels as body parts, highlights how physical limitations and environmental factors shape the evolution of traits, as seen in the absence of certain impossible phenotypes like laser-turret-wielding zebras or live-birth birds, illustrating the unique adaptability and creativity of evolution.

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Recent questions

  • Why do humans not have wings?

    Due to evolutionary constraints, each stage must provide a benefit.

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Summary

00:00

"Evolutionary Constraints: Forbidden Phenotypes and Adaptations"

  • Evolution raises questions about why certain traits are absent in nature, like humans not having wings or fish not having propellers.
  • The concept of "forbidden phenotypes" in evolution refers to traits that are impossible to evolve, like animals with wheels as body parts.
  • Animals like pangolins and spiders can roll up their bodies for movement, but no animal has wheels as body parts due to physical limitations.
  • The disappearance of wheeled vehicles like chariots in favor of camels in certain regions highlights how environmental factors influence adaptations.
  • Different cultures, like the Aztecs and Incas, did not use wheeled vehicles due to terrain and environmental factors, showing how adaptations are environment-dependent.
  • The fitness landscape concept explains how traits evolve based on their ability to survive and reproduce, with each stage needing to provide a benefit.
  • Evolutionary constraints prevent the development of traits like wings for humans, as each stage of evolution must be advantageous.
  • The example of zebras not evolving defensive weapons like laser turrets illustrates how intermediate steps in evolution must be beneficial.
  • The Trabant car's lack of improvement over decades in East Germany showcases how lack of selection pressure can hinder evolution.
  • Physics, specifically gravity and the square-cube law, impose limitations on the size and shape of organisms, influencing evolutionary possibilities.

15:23

"Evolution's Boundless Creativity: From Giant Insects to Plant-Eating Snakes"

  • The tallest tree on Earth reaches 130 meters, with the current tallest tree standing at just under 116 meters. Blue whales, weighing up to 173 tons, benefit from the buoyancy of their watery environment, allowing for larger sizes. Different planets with varying gravity or atmospheric compositions could potentially host larger animals than those on Earth.
  • Insects from 300 million years ago grew larger due to higher oxygen levels in the atmosphere, with some reaching sizes comparable to birds. Despite the vast diversity in nature, certain impossible phenotypes have yet to emerge, such as freshwater coral reefs, live-birth birds, and plant-eating snakes. Evolutionary possibilities remain open, with examples like spiders that eat plants challenging previous beliefs.
  • Evolutionary boundaries are not clearly defined, as seen in the potential for animals with odd numbers of limbs to evolve from even-numbered ancestors. Examples like dolphins moving with three "limbs" and starfish with five limbs showcase the remarkable adaptability and creativity of evolution in shaping diverse life forms.
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