A ancient unicellular organism would prove that yes, it is the chicken’s egg came first. In scientific terms, there is now evidence to suggest that the development of an embryo may have occurred before evolution.
In that single-celled organism, scientific name Chromosphaera perkinsiia research group led byUniversity of Geneva (Switzerland) has in fact identified one cell division similar to that of an animal embryo. And so yes, an “egg” could have developed before its “mom”.
The unicellular species was discovered in 2017 in marine sediments around Hawaii and the first signs of its presence on Earth have been dated to over a billion yearswell before the appearance of the first animals. But researchers have observed that this species forms multicellular structures that they present striking similarities with animal embryos.
According to scientists, these observations suggest that the genetic programs responsible for embryonic development were already present before the emergence of animal lifeor at least that Chromosphaera perkinsii it evolved independently by developing similar processes.
Research into the origin of life
For as long as it has existed (or almost) human beings have wondered how it was born life on Earth (and if we are really alone in the entire immense Universe.
One of the milestones of this research is certainly theMiller-Urey experiment: the two researchers, the other’s first student, in 1952 “bombarded” ammonia, water, hydrogen, carbon dioxide and methane with electric discharges.
The scientists built a simple but ingenious sterile system with which they wanted to somehow reconstruct the conditions thought likely on Earth before the appearance of lifewithout free oxygen but with abundant hydrogen, therefore without an atmosphere (or almost). The system was in particular made up of two spheres containing one liquid water and the other ammonia, hydrogen, carbon dioxide and methane, connected by two electrodes connected in turn through sealed tubes.
The experiment lasted about a week, during which the water was heated to induce the formation of water vapor while the two electrodes used to provide electric discharges simulating lightningand the whole apparatus was then cooled so that the water could recondense and fall back into the first sphere to repeat the cycle.
Well yes, after a week Miller he observed that about 15% of hydrogen had generated organic compounds, including some amino acids and other potential biological constituents. In other words organic matter was born from inorganic matter.
The first life forms that appeared on Earth were unicellular, that is, composed of a single cell, like yeast or bacteria. Subsequently, animals, multicellular organisms, evolved, developing from a single cell, the egg cell, to form complex beings. This embryonic development follows precise stages that are remarkably similar across animal species and could date back to a period well before the appearance of animals. However, the transition from unicellular species to multicellular organisms is still very poorly understood.
Did the egg really hatch first?
Chromosphaera perkinsii is an ancestral species of protist, which separated from the animal evolutionary lineage more than a billion years ago, offering valuable insights into the mechanisms that may have led to transition to multicellularity.
By observing it, scientists discovered that these cells, once they reach their maximum size, divide without growing any further, forming multicellular colonies that recall the initial stages of animal embryonic development.
Unprecedented, these colonies persist for about a third of their life cycle and comprise at least two distinct cell types, a surprising phenomenon for this type of organism.
Although C. perkinsii is a unicellular species, this behavior demonstrates that multicellular coordination and differentiation processes are already present in the species explains Omaya Dudin, who led the research – well before the first animals appeared on Earth
Even more surprisingly, the way these cells divide and the three-dimensional structure they adopt, the scientists note, are strikingly reminiscent of the early stages of embryonic development in animals.
It’s fascinating, a very recently discovered species allows us to go back in time over a billion years
comment Marine Olivettafirst author of the study
This discovery could also shed new light on a long-standing scientific debate about 600-million-year-old fossils that resemble embryos, and could challenge some traditional conceptions of multicellularity.
The work was published on Nature.
Sources: University of Geneva / Nature
