All articles tagged with #mammals
Camera-trap surveys in the Chernobyl Exclusion Zone reveal 11 mammal species—incl. Przewalski’s horses, Eurasian lynx and moose—are thriving in the largely human-free area, suggesting reduced disturbance supports wildlife even as scientists note the need for further study on lingering radioactivity effects.
Texas A&M researchers report a two-step, serum-driven process that turns local cells into a blastema and promotes limb-like regeneration in lab mice by first reducing scarring and then providing developmental signals, using resident cells rather than external stem cells; the approach could lessen scarring and broaden understanding of mammalian healing with potential human applications.
A Birmingham microbiologist proposes the longevity bottleneck hypothesis: during the age of dinosaurs, early mammals faced intense predation pressure and were selected for rapid reproduction, which may have led to the loss or inactivation of genes linked to long life. This long evolutionary pressure could help explain why mammals, including humans, age more quickly and have limited regenerative abilities compared with some other species.
A Birmingham microbiologist proposes the longevity bottleneck hypothesis: during the age of dinosaurs, mammals were pressured to reproduce quickly, leading to loss or inactivation of genes tied to long life. This evolutionary pressure could explain why humans and other mammals don’t exhibit extreme longevity or regenerative traits, though the idea remains a hypothesis that needs further testing.
A 250-million-year-old Lystrosaurus embryo fossil provides the first direct evidence that mammal ancestors laid eggs. High‑resolution imaging shows the embryo’s jaws were not fully fused, indicating an egg inside the egg with a soft leathery shell, suggesting water‑conserving eggs helped this dry‑habitat survivor endure the Great Dying. The discovery offers clues about the evolution of lactation and live birth, and implies that hatchlings were relatively mature at hatching, aiding early mammal lineages before milk secretion became widespread.
A Bristol-led study in Nature Geoscience finds that in about 250 million years, when a new supercontinent forms (Pangea Ultima), most land could be too hot and dry for mammals, but parts of southern Europe such as Spain may lie in a less extreme region due to latitude and proximity to the ocean. Conditions would still be harsh with high heat and limited rainfall, and the conclusion is not that Spain would be safe, but that it could be comparatively less severe; the research aims to understand how geography, atmosphere, and solar energy shape long‑term climate rather than predict livable refuges.
A fossil from Oviston, South Africa, shows the therapsid Lystrosaurus laid eggs about 252–250 million years ago. X-ray analysis revealed an in-egg embryonic beak not yet fused, indicating hatchlings that could break out of a leathery shell, a trait shared with turtles and birds and providing the first strong evidence that mammal ancestors laid eggs. This egg-based reproduction may have helped these creatures survive the Great Dying and reshapes our understanding of mammalian origins, alongside today’s egg-laying mammals like the platypus and echidna.
A Science study quantifies the pathogen spillover risk from the global wildlife trade: among 2,079 traded mammal species, about 41% share one or more pathogens with humans, compared with 6.4% of non-traded mammals. Live-trade increases transmission risk, illegal trade plays only a modest role, and species in trade tend to accumulate more pathogens over time (about one extra pathogen per decade of presence). The authors hope the findings inform trade regulations to help curb future pandemics.
A 20-year mouse cloning study from the University of Yamanashi shows that repeating cloning builds up genome-level damage, reduces fertility, and cannot sustain a mammal line beyond 58 generations—the last generation died soon after birth—despite producing over 1,200 clones from a single donor, indicating current nuclear-transfer cloning methods have a hard biological limit.
A two-decade Japanese study recloned a female mouse across 58 generations. By generation 58, all offspring died within a day of birth, with no outward defects, and DNA analysis showed accumulating mutations and occasional loss of an X chromosome. The research indicates a hard limit to mammalian cloning and challenges hopes for infinite lineages, with implications for livestock cloning and de-extinction efforts; no method yet exists to overcome this genetic deterioration.
A Japanese team conducted a serial cloning study starting from one female mouse, re-cloning for 57 generations and producing over 1,200 offspring. By generation 58, accumulated genetic mutations and loss of the X chromosome caused the re-cloned mice to die shortly after birth, effectively ending the line. Crossbreeding later-generation clones with normal mice showed initially normal litter sizes but reduced fertility in later-generation lines, with partial recovery in descendants. The results support Muller's ratchet and reinforce the idea that sexual reproduction is essential for long-term mammalian survival, limiting the practical viability of endless cloning.
A mega-analysis of 117 mammal species shows that restricting reproduction—via contraception or sterilization—can extend life expectancy by about 10%, with male lifespans increasing when testosterone is reduced through castration (vasectomy effects vary), and females living longer when reproduction is blocked. The results point to energetic and hormonal costs of reproduction as a trade-off with survival, though effects vary by species and context, and human implications remain uncertain.
New research shows that elephants’ trunk whiskers are highly sensitive, enabling refined tactile sensing and vibration detection that support complex trunk manipulation and environmental awareness, expanding our understanding of elephant sensory biology.
CT scans and 3D simulations of the 250‑million‑year‑old cynodont Thrinaxodon liorhinus indicate ear structures capable of tympanic (ear‑based) hearing emerged earlier than previously thought, suggesting the mammalian middle ear began evolving before dinosaurs; the model estimates a hearing range of about 38–1,243 Hz with peak sensitivity near 1,000 Hz at ~28 dB, aiding prey detection and predator avoidance.
A large-scale study finds that preventing reproduction in mammals, through methods like sterilization or contraception, is associated with increased lifespan, highlighting the biological costs of reproduction and its impact on aging across species, including potential insights for humans.