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Placental Mammal
Context:
New research from Stockholm University shows that the typical mammalian heater organ, brown fat, evolved exclusively in modern placental mammals.
Evolution of Brown Fat in Mammals:
- Evolutionary Milestone: Around 100 million years ago, placental mammals underwent a significant evolutionary shift that allowed them to diversify and thrive in colder regions.
- This shift coincided with the development of a crucial heat-producing organ, brown fat.
- Research indicates that brown fat evolved exclusively in modern placental mammals.
- Marsupials, distant relatives of placental mammals, possess a less evolved form of brown fat.
- Study helps in tracing the origin of brown adipose tissue.
- The emergence of brown fat provides insights into mammalian adaptation to environmental challenges.
- Key Protein: The pivotal heat-producing protein known as UCP1 became active after the divergence of placental and marsupial mammals.
- Brown fat, utilising UCP1, regulates body temperature in newborns and contributes to metabolic health by metabolising fat and sugars.
- the UCP1 protein in marsupials does not produce heat.
- Understanding the role of brown fat in mammalian evolution sheds light on aspects such as endothermy and metabolism.
- Implications for Human Health: Brown fat’s energy-consuming function is potential to address obesity, diabetes, and cardiometabolic diseases.
- Integrating evolutionary insights into understanding human metabolic diseases could lead to novel therapeutic approaches
About Placental Mammal:
- Placental mammals belong to the infraclass Eutheria, characterised by the presence of a placenta, a vascular organ that develops during gestation.
- The placenta facilitates the exchange of nutrients and wastes between the blood of the mother and that of the foetus.
- They encompass all living mammals except marsupials and monotremes (egg-laying mammals).
- Marsupials, though sometimes categorised as placental mammals, possess a less-developed placenta, limiting gestation.
- The advanced placenta of placental mammals allows for extended gestational periods, contributing to their evolutionary success.
- Fossil evidence suggests placental mammals emerged between 163 to 157 million years ago during the Jurassic Period.
- Some scientists use the clade Placentalia to classify placental mammals, aiming to avoid confusion with extinct non placental eutherians.
About Marsupials:
- They belong to the infraclass Metatheria, characterised by premature birth and continued development of the newborn while attached to the mother’s nipples.
- They possess an additional pubic bone known as the epipubic bone, which aids in supporting their pouch.
- Marsupials exhibit structural and behavioural parallels with placental mammals, a phenomenon known as convergent evolution.
- Marsupials fill various ecological niches, such as burrowing, terrestrial, gliding, and arboreal lifestyles.
- Marsupials comprise over 330 species, with approximately two-thirds inhabiting Australia and the remaining third primarily found in South America. Examples of marsupials include kangaroos, koalas, and opossums.
