![](http://pinterest.com/pin/create/button/?url=http://trecnews4u.blogspot.com/2014/04/homo-adalah-hanya-primata-yang.html&media=https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjP1rm2U5D0VaJ8U3JJp1mETBj4a-hxxbvRRatuSjh4Ls1Rv_TlLXmm4uQKUOmiIf1Kxs4rfv_EAeP1fDz_za6Nou2AIHMxJa3bhhu-1QeYjXcD7DVYJocKxQEbn5MObqFAf3H5PjO_HWW8/s72-c/homo-aninews+dot+in.jpg&description=....SILAHKAN MENGGUNAKAN " MESIN TRANSLATE "..GOOGLE TRANSLATEÂ DISAMPING KANAN INI............. PLEASE USE ........ "...){kind=link}
DISAMPING KANAN INI.............
PLEASE USE ........ "TRANSLATE MACHINE" .. GOOGLE TRANSLATE BESIDE RIGHT THIS
....................
'Homo'
is the only primate whose tooth size decreases as its brain size increases
'Homo'
is the only primate whose tooth size decreases as its brain size increases
Date:
April 3,
2014
Source:
University of Granada
Summary:
Scientists have discovered a curious characteristic of
the members of the human lineage, classed as the genus Homo: they are the only
primates where, throughout their 2.5-million year history, the size of their
teeth has decreased in tandem with the increase in their brain size.
............................
Andalusian
researchers, led by the University of Granada, have discovered a curious
characteristic of the members of the human lineage, classed as the genus Homo:
they are the only primates where, throughout their 2.5-million year history,
the size of their teeth has decreased in tandem with the increase in their brain
size.
The key to
this phenomenon, which scientists call "evolutionary paradox," could
be in how Homo's diet has evolved. Digestion starts first in the mouth and, so,
teeth are essential in breaking food down into smaller pieces. Therefore, the
normal scenario would be that, if the brain grows in size, and, hence, the
body's metabolic needs, so should teeth.
However, in
the case of Homo, this has not been the case, according to scientists in an
article recently published in the journal BioMed Research International.
The main author of the study, researcher Juan Manuel Jimenez Arenas, from the
University of Granada's Department of Pre-History and Archaeology, points out
that, "This means that significant changes must have occurred in order to
maintain this trend."
A change in
diet, incorporating a higher amount of animal food, must have been one of the
keys to this phenomenon. The quality leap in Homo's diet, through a greater
intake in animal proteins, fats and certain olio-elements, is essential for a
correct working and maintenance of the brain. On a similar note, a larger brain
allows greater social and cultural development, which, at that time, led to the
achievement of important technological innovations.
In order to
validate this theory, the researchers evaluated the relationship between the
size of post-canine teeth and the volume of the endocranium in a wide set of
primates, among which were found the main representatives of Homo fossils.
"Before we started the study, it was well known that, throughout the
evolution of humans, tooth-size diminished and brain-size increased. We have
established that they are two opposing evolutionary trends that have been
linked for 2.5 million years, when our first ancestors within the Homo genus
first appeared on the evolutionary stage."
Genetic
Study
The study's
authors also relate these changes to the inactivation of gene MYH16, linked to
temporalis musculature, which fell in size approximately 2.4 million years ago.
This would do away with an important barrier for encephalization (a
hypertrophied temporalis musculature prevents the development of the cranial
dome). Likewise, they analyzed their relationship with the inactivation of gene
SRGAP2, which helps towards the evolution of the neo-cortex, playing a principal
role in human brain development.
Story
Source:
The above
story is based on materials provided by University of Granada. Note: Materials may be
edited for content and length.
Journal
Reference:
- Juan Manuel Jiménez-Arenas, Juan Antonio Pérez-Claros, Juan Carlos Aledo, Paul Palmqvist. On the Relationships of Postcanine Tooth Size with Dietary Quality and Brain Volume in Primates: Implications for Hominin Evolution. BioMed Research International, 2014; 2014: 1 DOI: 10.1155/2014/406507
Cite This
Page:
University of Granada. "'Homo'
is the only primate whose tooth size decreases as its brain size
increases." ScienceDaily. ScienceDaily, 3 April 2014.
<www.sciencedaily.com/releases/2014/04/140403095415.htm>.
