Early modern human from Southeast Asia adapted to a rainforest
environment
New insights into the diet of our species' earliest member in the
tropical rainforest of Southeast Asia

Date:
October 14, 2021
Source:
Max Planck Institute for Evolutionary Anthropology
Summary:
Although there has been evidence of our species living in rainforest
regions in Southeast Asia from at least 70,000 years ago, the
poor preservation of organic material in these regions limits how
much we know about their diet and ecological adaptations to these
habitats. An international team of scientists has now applied a
new method to investigate the diet of fossil humans: the analysis
of stable zinc isotopes from tooth enamel. This method proves
particularly helpful to learn whether prehistoric humans and
animals were primarily eating meat or plants.



FULL STORY ========================================================================== Traditional assumptions have often seen tropical rainforests as a barrier
to early Homo sapiens. However, growing proof shows that humans adapted
to and lived in tropical rainforest habitats of Southeast Asia. Some researchers also suggest that, in the past, other human species, like
Homo erectus and Homo floresiensis, became extinct because they could
not adapt to this environment as our species did. However, we know very
little about the ecological adaptation of fossil humans, including what
they were eating.


==========================================================================
Zinc isotopes reveal what kind of food was primarily eaten In this study, researchers analysed the zinc stable isotope ratios from animal and human
teeth from two sites in the Hua` Pan Province of Laos: Tam Pa` Ling and
the nearby site of Nam Lot. "The site of Tam Pa` Ling is particularly
important for palaeoanthropology and archaeology of Southeast Asia because
it holds the oldest and most abundant fossil record of our species in
this region," explains Fabrice Demeter, researcher at the University
of Copenhagen.

However, there is little archaeological evidence, like stone tools,
hearth features, plant remains, cut marks on bones, in Tam Pa` Ling:
only teeth and bones. This makes isotopic approaches the only way to
gain insight into past dietary reliance.

Nitrogen isotope analysis, in particular, can help scientists learn
if past humans were eating animals or plants. However, the collagen in
bones and teeth needed to do these analyses is not easily conservable. In tropical regions like the one at Tam Pa` Ling this problem is even more
acute. "New methods -- such as zinc isotope analysis of enamel -- can
now overcome these limitations and allow us to investigate teeth from
regions and periods we could not study before," says study leader Thomas Tu"tken, professor at the Johannes Gutenberg University's Institute of Geosciences. "With zinc stable isotope ratios, we can now study Tam Pa`
Ling and learn what kind of food our earliest ancestors in this region
were eating." First study that reveals the whole diet of fossil humans
from Southeast Asia The fossil human studied in this research dates from
the Late Pleistocene, more precisely from 46,000 to 63,000 years ago. With
it, various mammals from both sites, including water buffaloes, rhinos,
wild boars, deer, bears, orangutans, macaques, and leopards, were also analysed. All these different animals show various eating behaviours,
making for an ideal background to determine what exactly humans were
eating at the time. The more diverse the animal remains found at a
particular site are, the more information the researchers can use to
understand the diet of prehistoric humans.

When we compare the zinc isotope values from the fossil Homo sapiens
of Tam Pa` Ling to that of the animals, it strongly suggests that its
diet contained both plants and animals. This omnivorous diet also
differs from most nitrogen isotope data of humans in other regions
of the world for that time period, where a meat-rich diet is almost consistently discerned. "Another kind of analysis performed in this
study -- stable carbon isotopes analysis - - indicates that the food
consumed came strictly from forested environments," says E'lise Dufour, researcher at the National Natural History Museum of Paris.

"The results are the oldest direct evidence for subsistence strategies
for Late Pleistocene humans in tropical rainforests." Researchers often associated our species with open environments, like savannahs or cold
steppes. However, this study shows that early Homo sapiens could adapt
to different environments. Together, the zinc and carbon isotope results
may suggest a mix of specialized adaptations to tropical rainforests seen
from other Southeast Asian archaeological sites. "It will be interesting,
in the future, to compare our zinc isotope data with data from other prehistoric human species of Southeast Asia, like Homo erectus and Homo floresiensis, and see if we could understand better why they went extinct
while our species survived," concludes first author Nicolas Bourgon,
a researcher at the Max Planck Institute for Evolutionary Anthropology.

========================================================================== Story Source: Materials provided by Max_Planck_Institute_for_Evolutionary_Anthropology. Note: Content may
be edited for style and length.


========================================================================== Journal Reference:
1. Nicolas Bourgon et al. Trophic ecology of a Late Pleistocene
early modern
human from tropical Southeast Asia inferred from
zinc isotopes. Journal of Human Evolution, 2021 DOI:
10.1016/j.jhevol.2021.103075 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/10/211014141955.htm

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