Scientists discover why fish evolved limbs and left water

Researchers find a key clue to the evolution of bony fish and tetrapods.

Scientists discover why fish evolved limbs and left water

Fish and tetrapods.

Credit: Karen Carr © The Field Museum
  • A new study says solar and lunar tide impacts led to the evolution of bony fish and tetrapods.
  • The scientists show that tides created tidal pools, stranding fish and forcing them to get out of the water.
  • The researchers ran computer simulations to get their results.

Tides influenced by the sun and the moon were likely the reason why fish developed limbs and early tetrapods evolved, found new research.

The groundbreaking study took a look at tides during the Late Silurian—Devonian periods, which happened between 420 million years ago and 380 million years ago.

The scientists built their work on the theory that the Moon's mass and specific location along its orbit can greatly affect vast tidal ranges across Earth and can create tidal pools. Because they are isolated from each other, the pools provided the biological motivation for fish stranded by high tides to eventually grow limbs.

The study involved researchers from UK's Bangor University and Oxford University as well as Uppsala University in Sweden. They devised very detailed numerical simulations that proved the existence of large tides during the period they studied. They are first to tie tidal hydrodynamics to an evolutionary biological event, states the press release from the University of Oxford.

To come up with the simulations, the scientists employed paleogeography, the study of historical geography, to reconstruct the Earth's continents within the numerical model. The calculations showed tides over four meters happening around the South China block. That area holds the known origin site of the earliest bony fish we know and has been a treasure-trove of the earliest fossils of that nature. Geological evidence also supports changes in tides to be lined to these fossils.

Neil deGrasse Tyson Explains the Tides

"Large tidal ranges could have fostered both the evolution of air-breathing organs in osteichthyans to facilitate breathing in oxygen-depleted tidal pools, and the development of weight-bearing tetrapod limbs to aid navigation within the intertidal zones," states the paper.

The researchers believe further tidal simulations from early Earth can be used to recreate that far past with greater detail. The findings can help us understand more what roles tides played in diversifying early vertebrates or in causing extinction events.

Check out the study published in Proceedings of the Royal Society A.


A historian identifies the worst year in human history

A Harvard professor's study discovers the worst year to be alive.

The Triumph of Death. 1562.

Credit: Pieter Bruegel the Elder. (Museo del Prado).
Politics & Current Affairs
  • Harvard professor Michael McCormick argues the worst year to be alive was 536 AD.
  • The year was terrible due to cataclysmic eruptions that blocked out the sun and the spread of the plague.
  • 536 ushered in the coldest decade in thousands of years and started a century of economic devastation.
Keep reading Show less

Study: You would spend 90 extra days in jail in a private prison

A new study suggests that private prisons hold prisoners for a longer period of time, wasting the cost savings that private prisons are supposed to provide over public ones.

Politics & Current Affairs
  • Private prisons in Mississippi tend to hold prisoners 90 days longer than public ones.
  • The extra days eat up half of the expected cost savings of a private prison.
  • The study leaves several open questions, such as what affect these extra days have on recidivism rates.
Keep reading Show less

Want to live 100+ years? You may need unusually good DNA repair

A new study finds an unusual genetic difference in people over 105.

The world's oldest living person celebrates her 116th birthday.

Credit: JIJI PRESS via Getty Images
Surprising Science
  • Researchers conduct genetic analyses of 81 Italian people who are over 105 years in age.
  • Five unusual genetic differences were discovered.
  • The differences are implicated in the routine repair of DNA, which seems to work unusually well in these people.
Keep reading Show less
Quantcast