The difference between fish and humans: Scientists answer century-old developmental question

Oct 10, 2007

Embryologists at UCL (University College London) have helped solve an evolutionary riddle that has been puzzling scientists for over a century. They have identified a key mechanism in the initial stages of an embryo’s development that helps differentiate more highly evolved species, including humans, from less evolved species, such as fish. The findings of the research were published online today by the journal Nature.

Early on in development, the mass of undifferentiated cells that make up the embryo must take the first steps in deciding how to arrange themselves into component parts to eventually go on to form a fully developed body. This is a process known as ‘gastrulation’.

During this stage, the cells group into three layers, the first is the ‘ectoderm’ which then in turn generates the ‘mesoderm’ and ‘endoderm’ layers. In higher vertebrates, such as mammals and birds, the mesoderm and endoderm are generated from an axis running through the centre of the embryo. However, in lower vertebrates, such as amphibians and fish, the two layers are generated around the edge of the embryo.

Using chicken eggs and a state-of-the-art imaging device which can reveal how cells move in three dimensions, the researchers demonstrated a key difference in the way gastrulation occurs between higher vertebrate species and less evolutionarily advanced animals. They discovered that the reason why higher vertebrates form their axis at the midline of the embryo is because during evolution they acquired a new mechanism of “cell intercalation” which positions the axis at the midline. They also discovered the molecules used by the embryo to control these cell movements.

Scientists have been speculating for over a century on the difference between the embryonic development of higher vertebrates and lower vertebrates, to help answer how the simple cell structure of an embryo goes on to form the various highly complex bodies of different species. Research leader Prof Claudio Stern explains: “This is a significant find as it is a clear difference between the embryonic development of more advanced species and less advanced species. It suggests that higher vertebrates must have developed this mechanism later on in the history of animal evolution.

In humans this process occurs during week 3 of embryonic development, and forms the cut-off point for scientific research on human embryos in the UK.

Source: Biotechnology and Biological Sciences Research Council

Explore further: Protein merlin regulates collective cell movement, promoting effective and rapid wound healing

add to favorites email to friend print save as pdf

Related Stories

Evolving robot brains

10 hours ago

Researchers are using the principles of Darwinian evolution to develop robot brains that can navigate mazes, identify and catch falling objects, and work as a group to determine in which order they should ...

Facebook fends off telecom firms' complaints

10 hours ago

Facebook founder Mark Zuckerberg fended off complaints on Monday that the hugely popular social network was getting a free ride out of telecom operators who host its service on smartphones.

Scientists find clues to cancer drug failure

10 hours ago

Cancer patients fear the possibility that one day their cells might start rendering many different chemotherapy regimens ineffective. This phenomenon, called multidrug resistance, leads to tumors that defy ...

Glass coating improves battery performance

10 hours ago

Lithium-sulfur batteries have been a hot topic in battery research because of their ability to produce up to 10 times more energy than conventional batteries, which means they hold great promise for applications ...

Recommended for you

The environmental impact of cats on native wildlife

56 minutes ago

A team of researchers, led by Dr Wayne Linklater from the Centre for Biodiversity and Restoration Ecology at Victoria University of Wellington, recently surveyed veterinarians and cat owners to understand ...

Human and animal interaction identified in the viking age

1 hour ago

Since 2001, ancient DNA has been used in paleoparasitological studies to identify eggs found in soil samples from prehistoric periods, because identification cannot be done by morphological study alone. The species of human ...

Ringling elephants say goodbye to the circus

14 hours ago

Across America through the decades, children of all ages delighted in the arrival of the circus, with its retinue of clowns, acrobats and, most especially, elephants.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.