http://www.bbk.ac.uk/bih/events
Start 04 October 2017 - 14:00 hours
End 04 October 2017 - 16:00 hours
Located at Birkbeck,
University of London, Room B01, Clore Management Centre, London WC1E 7JL
Friday, September 1, 2017
Fossil footprints challenge established theories of human evolution
Date: August 31, 2017
Source: Uppsala University
Summary: Newly discovered
human-like footprints from Crete may put the established narrative of early
human evolution to the test. The footprints are approximately 5.7 million years
old and were made at a time when previous research puts our ancestors in Africa
-- with ape-like feet.
Newly discovered human-like
footprints from Crete may put the established narrative of early human
evolution to the test. The footprints are approximately 5.7 million years old
and were made at a time when previous research puts our ancestors in Africa --
with ape-like feet.
Ever since the discovery of
fossils of Australopithecus in South and East Africa during the middle years of
the 20th century, the origin of the human lineage has been thought to lie in
Africa. More recent fossil discoveries in the same region, including the iconic
3.7 million year old Laetoli footprints from Tanzania which show human-like
feet and upright locomotion, have cemented the idea that hominins (early
members of the human lineage) not only originated in Africa but remained
isolated there for several million years before dispersing to Europe and Asia.
The discovery of approximately 5.7 million year old human-like footprints from Crete,
published online this week by an international team of researchers, overthrows
this simple picture and suggests a more complex reality.
Human feet have a very
distinctive shape, different from all other land animals. The combination of a
long sole, five short forward-pointing toes without claws, and a hallux
("big toe") that is larger than the other toes, is unique. The feet
of our closest relatives, the great apes, look more like a human hand with a
thumb-like hallux that sticks out to the side. The Laetoli footprints, thought
to have been made by Australopithecus, are quite similar to those of modern
humans except that the heel is narrower and the sole lacks a proper arch. By
contrast, the 4.4 million year old Ardipithecus ramidus from Ethiopia, the oldest
hominin known from reasonably complete fossils, has an ape-like foot. The
researchers who described Ardipithecus argued that it is a direct ancestor of
later hominins, implying that a human-like foot had not yet evolved at that
time.
The new footprints, from
Trachilos in western Crete, have an unmistakably human-like form. This is
especially true of the toes. The big toe is similar to our own in shape, size
and position; it is also associated with a distinct 'ball' on the sole, which
is never present in apes. The sole of the foot is proportionately shorter than
in the Laetoli prints, but it has the same general form. In short, the shape of
the Trachilos prints indicates unambiguously that they belong to an early
hominin, somewhat more primitive than the Laetoli trackmaker. They were made on
a sandy seashore, possibly a small river delta, whereas the Laetoli tracks were
made in volcanic ash.
'What makes this controversial
is the age and location of the prints,' says Professor Per Ahlberg at Uppsala
University, last author of the study.
At approximately 5.7 million
years, they are younger than the oldest known fossil hominin, Sahelanthropus
from Chad, and contemporary with Orrorin from Kenya, but more than a million
years older than Ardipithecus ramidus with its ape-like feet. This conflicts
with the hypothesis that Ardipithecus is a direct ancestor of later hominins.
Furthermore, until this year, all fossil hominins older than 1.8 million years
(the age of early Homo fossils from Georgia) came from Africa, leading most
researchers to conclude that this was where the group evolved. However, the
Trachilos footprints are securely dated using a combination of foraminifera
(marine microfossils) from over- and underlying beds, plus the fact that they
lie just below a very distinctive sedimentary rock formed when the
Mediterranean sea briefly dried out, 5.6 millon years ago. By curious
coincidence, earlier this year, another group of researchers reinterpreted the
fragmentary 7.2 million year old primate Graecopithecus from Greece and
Bulgaria as a hominin. Graecopithecus is only known from teeth and jaws.
During the time when the
Trachilos footprints were made, a period known as the late Miocene, the Sahara
Desert did not exist; savannah-like environments extended from North Africa up
around the eastern Mediterranean. Furthermore, Crete had not yet detached from
the Greek mainland. It is thus not difficult to see how early hominins could
have ranged across south-east Europe and well as Africa, and left their footprints
on a Mediterranean shore that would one day form part of the island of Crete.
'This discovery challenges the
established narrative of early human evolution head-on and is likely to
generate a lot of debate. Whether the human origins research community will
accept fossil footprints as conclusive evidence of the presence of hominins in
the Miocene of Crete remains to be seen,' says Per Ahlberg.
Gut bacteria that 'talk' to human cells may lead to new treatments
Date: August 30, 2017
Source: Rockefeller University
Summary: Scientists developed
a method to genetically engineer gut bacteria to produce molecules that have
the potential to treat certain disorders by altering human metabolism.
We have a symbiotic
relationship with the trillions of bacteria that live in our bodies -- they
help us, we help them. It turns out that they even speak the same language. And
new research from The Rockefeller University and the Icahn School of Medicine
at Mt. Sinai suggests these newly discovered commonalities may open the door to
"engineered" gut flora who can have therapeutically beneficial
effects on disease.
"We call it
mimicry," says Sean Brady, director of Rockefeller University's Laboratory
of Genetically Encoded Small Molecules, where the research was conducted. The
breakthrough is described in a paper published this week in the journal Nature.
In a double-barreled
discovery, Brady and co-investigator Louis Cohen found that gut bacteria and
human cells, though different in many ways, speak what is basically the same
chemical language, based on molecules called ligands. Building on that, they
developed a method to genetically engineer the bacteria to produce molecules
that have the potential to treat certain disorders by altering human
metabolism. In a test of their system on mice, the introduction of modified gut
bacteria led to reduced blood glucose levels and other metabolic changes in the
animals.
Molecular impersonation
The method involves the
lock-and-key relationship of ligands, which bind to receptors on the membranes
of human cells to produce specific biological effects. In this case, the
bacteria-derived molecules are mimicking human ligands that bind to a class of
receptors known as GPCRs, for G-protein-coupled receptors.
Many of the GPCRs are
implicated in metabolic diseases, Brady says, and are the most common targets
of drug therapy. And they're conveniently present in the gastrointestinal
tract, where the gut bacteria are also found. "If you're going to talk to
bacteria," says Brady, "you're going to talk to them right
there." (Gut bacteria are part of the microbiome, the larger community of
microbes that exist in and on the human body.)
In their work, Cohen and Brady
engineered gut bacteria to produce specific ligands, N-acyl amides, that bind
with a specific human receptor, GPR 119, that is known to be involved in the
regulation of glucose and appetite, and has previously been a therapeutic
target for the treatment of diabetes and obesity. The bacterial ligands they
created turned out to be almost identical structurally to the human ligands,
says Cohen, an assistant professor of gastroenterology in the Icahn School of
Medicine at Mt. Sinai.
Manipulating the system
Among the advantages of
working with bacteria, says Cohen, who spent five years in Brady's lab as part
of Rockefeller's Clinical Scholars Program, is that their genes are easier to
manipulate than human genes and much is already known about them. "All the
genes for all the bacteria inside of us have been sequenced at some
point," he says.
In past projects, researchers
in Brady's lab have mined microbes from soil in search of naturally occurring
therapeutic agents. In this instance, Cohen started with human stool samples in
his hunt for gut bacteria with DNA he could engineer. When he found them he
cloned them and packaged them inside E. coli bacteria, which is easy to grow.
He could then see what molecules the engineered E. coli strains were making.
Although they are the product
of non-human microorganisms, Brady says it's a mistake to think of the
bacterial ligands they create in the lab as foreign. "The biggest change
in thought in this field over the last 20 years is that our relationship with
these bacteria isn't antagonistic," he says. "They are a part of our
physiology. What we're doing is tapping into the native system and manipulating
it to our advantage."
"This is a first step in
what we hope is a larger-scale, functional interrogation of what the molecules
derived from microbes can do," Brady says. His plan is to systematically
expand and define the chemistry that is being used by the bacteria in our guts
to interact with us. Our bellies, it turns out, are full of promise.
Story Source:
Materials provided by Rockefeller University. Note: Content may be edited for
style and length.
India: Torrential monsoon rains paralyze Mumbai and devastate Bihar State
https://www.youtube.com/watch?v=Koj9k49zxIc
Brotherhood & unity through irony and jokes about stereotypes
https://www.youtube.com/watch?v=bdgHTjUmDII
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