Arxiu d'etiquetes: bipedalism

Pangolin: poaching is condemning it to extinction

Neither the tiger or elephant or rhino: the most hunted mammals by humans are pangolins, to the point of critically threaten their survival as a species. Discover the only mammal with scales, its current condition and what can we do to prevent the extinction of all species of pangolin in the world.

WHAT IS A PANGOLIN?

manis tricuspis, pangolin, árbol, tree, trepando
Tree pangolin (Phataginus tricuspis). (Photo by Bart Wursten).

The name pangolin (also known as scaly anteater or trenggiling) includes 8 different species distributed by a variety of habitats (tropical rainforests, dry forests, savanna areas, cultivated fields…) in Africa and Asia. They measure between 90 cm and 1.65 m. They are the only family in the order Pholidota: although physically similar, armadillos, sloths and anteaters are not its relatives (order Xenarthra). Most are nocturnal, solitary and shy, so there are still many questions about their biology and behavior in the wild (they don’t usually survive captivity).

MORPHOLOGY

Pangolins are the only mammals with scales: they are made of keratin (like our nails) and give them a look like a pineapple or artichoke. Scales are very sharp and they can move them voluntarily. If pangolins feel threatened hiss and puff, curl into a ball leaving the scales exposed and secrete pestilential acids to ward off predators (tigers, lions, panthers and humans).

leon, leona, pangolin, bola, lion, defensa
An impenetrable defense even to a lioness. (Photo by Holly Cheese)

The claws allow them both climb as digging: terrestrial pangolins hide and breed in underground galleries and arboreal pangolins do the same in hollows on trees. The tail of the tree pangolin is prehensile to attach to the branches. In addition, pangolins are excellent swimmers.
They are mainly bipedal animals: forepaws are so large that force them to walk on its hind legs, with a maximum speed of 5 km/h. Watch a pangolin walking and feeding:

NUTRITION

Pangolin has no teeth and is unable to chew. It feeds on ants and termites, which locates with its powerful sense of smell (the view is underdeveloped) and catch them with its sticky and long tongue (may be longer than the body itself, up to 40 cm). The stones swallowed involuntarily and corneal structures of their stomach help them to crush the exoskeletons of insects. With its powerful claws destroy their nests to access them and avoid their attack plugging his ears and nostrils, besides having an armored eyelid. It is estimated that a pangolin can consume about 70 million insects per year, which makes them important regulators of the population of ants and termites.

lengua, pangolin, tongue
The tongue of the pangolin. (Photo by Wim Vorster).

REPRODUCTION

Pangolins can reproduce at any time of the year. After pregnancy (two to five months, depending on species) only one young is born (African species) or up to three (Asian species).

pangolin, hembra, female, mamas, breast, pecho, tetas
Female pangolin. (Photo by Scott Hurd)

The pangolin is born with soft scales, which begin to harden after two days. When after a month come out of the burrow, they travel on the tail of her mother and become independent at 3-4 months. Their lifespan is unknown, although in captivity an individual lived until 20 years old.

pangolin, baby, cría, zoo bali
Female with her baby in the tail. Bali zoo. (Photo by Firdia Lisnawati)

THREATS AND CONSERVATION

In addition to habitat destruction, the main threat that pangolins face is direct hunting for human consumption. Although there are international laws to protect them, it is estimated that about 100 000 pangolins are hunted annuallyGiven the defense strategy of this animal, poachers only have to catch them of the ground. Like other species, like sharks, the food market and traditional medicine are the main causes of directing the pangolin towards extinction.

pangolin, jaulas, tráfico ilega, illegal trade, bushmeat
Illegal trade in pangolin. (Photo by Soggydan Benenovitch).

WHY PANGOLINS ARE POACHED?

  • Bushmeat is considered a delicacy and an indicator of high social status in Vietnam and China. The pangolin fetus soup is sold as an elixir to increase virility and improve breast milk production. The price of bushmeat on the black market can reach $ 300 per kilo. The price of an individual can reach $ 1,000.

sopa, feto, soup, pangolin, feto, fetus
Pangolin fetus soup. (Photo by TRAFFIC).

  • Blood is sold as a tonic to improve health and as an aphrodisiac.
  • Scales can reach $ 3000 per kilo and are used for almost anything: to cure from acne to cancer. This belief is curious, considering that the scales have the same structure as our fingernails.

pangolín, china, medicina, medicine, tradicional, cura para el cáncer
Products of traditional Chinese medicine made of pangolin. (Photo by TRAFFIC).

All these purported medicinal and magical effects have no scientific basis, making yet more nonsense pangolin smuggling.

CONSERVATION

The population trend of all species of pangolin is declining in some cases to an alarming extent. The IUCN (International Union for the Conservation of Nature) Red List of Threatened Species classifies them as it follows:

RED LIS CATEGORIES IUCN
IUCN Red List categories. (Image from iucn.org)

Because of their status, IUCN restored in 2012 a group of specialists within the Species Survival Commission (SSC) dedicated to pangolins (Pangolin Specialist Group -PangolinSG-). Its main objective are do research to increase knowledge of pangolins, the threats they face and how they can be mitigated to facilitate preservation.

The conservation projects that are being carried out include campaigns to reduce the demand of bushmeat and pangolin scales and the tightening of laws. Still, the total ignorance of populations’ state and low survival in captivity for breeding makes it difficult to design strategies for their conservation.

WHAT CAN YOU DO FOR PANGOLIN?

  • Reject any product derived from this animal, either bushmeat, scales or “miracle” products for the cure of diseases. Read the labels of any traditional remedies, especially if they are from the Asian market, and recall that its hypothetical benefits have no scientific basis, so that you can rethink their use.
  • Share information. If you own new data on pangolins, photos or videos contact with PangolinSG to cooperate with the investigation. Talk about them in your immediate environment to raise awareness and publicize this fantastic single animal.
  • Do a PhD about pangolins. Lot of research on these species is still needed, so if you are a student and you are planning to do a PhD, you can collaborate with PangolinSG with your future research.
  • Become a PangolinSG volunteer. Get involved in the development and implementation of projects and conservation programs.
  • Make a financial donation so PangolinSG can continue its work.

In conclusion, more scientific research, a change of mind and protection policies are needed to prevent the pangolin become an example of extinct species at the hands of ours, as it is about to happen to white rhino.

REFERENCES

MIREIA QUEROL ALL YOU NEED IS BIOLOGY

Hands-free in the Pliocene

In the previous post we discovered the anatomical changes associated with bipedalism in early hominids and the relationship of the selection of this feature with climate change. Is bipedalism a trait that makes us human? What are the advantages over other quadruped animals?

WHAT IS THE PLIOCENE?

Since the origin of our planet, geologists have divided time into different divisions of millions of years: the eons (Archean, Proterozoic and Phanerozoic), which in turn are divided into different eras. The Phanerozoic (from 542 Ma to present) is divided into three eras, from oldest to newest: Paleozoic, Mesozoic and Cenozoic. In this link you can see  the major biological milestones for each epoch.

cenozoic
Cenozoic detail. Full image

The Miocene is the time when the hominoids appear, (Proconsul is the most famous genus) and in the Pliocene appears, among others, Australopithecus. Homo sapiens do not appear until the Holocene, a blink in the planet’s history, as they say.

Usually the climate changes that have been happening throughout the history of Earth, represent extinction, diversification and new species, and so does our evolutionary branch: many authors relate climatic fluctuations with milestones of hominins. If you are interested in this interactive you can investigate this issue.

slideshow_plate_tectonics_02
Position of the continents in the Miocene after the collision between the Eurasian and Indica plates. (Photo by The Burgess Shale)

One of these climatic changes (caused by the collision of the Eurasian and Indica tectonic plates,  giving rise to the Himalayas and changing wind currents) was responsible for the disappearance of large tracts of rainforest, giving way to a landscape shrub or savanna. Hominoids who stayed in the forest, led to the current nonhuman apes, while those who occupied the savannatrees mosaic led to hominins, our lineage. What are the advantatges of bipedalism in that landscape?

ADVANTATGES OF BIPEDALISM

  • Handsfree: the two free limbs can be used to transport food and offspring. You can reach fruit trees without stepping on them and later, will allow the manipulation of tools, hunting and cultural events.
  • Less heat: without offering the entire back surface to the sun, and separating the body from the hot ground, it allows cope better with high temperatures and survive with less water.
  • More energy: walking on two legs consumes less energy than walking on four. This allow walking longer distances with less food, which is important in an environment where you have to flee or find food constantly. We have a great strength to walk or run many kilometers compared with quadrupeds.
  • Best visual field: the eyes have a higher position and can detect potential predators over shrubs or drive them away with stones if necessary. It is also easier to spot food sources.
  • Intimidating appearance: upright posture appears to increase body size and can avoid confrontations with certain predators.
  • Better communication: the insertion of the skull with the spine, leaving enough space for the vocal cords allow, over time, the appearance of articulate speech. Although other apes had the same brain capacity to talk, morphologically it is impossible because of the structure of their vocal apparatus.
Algunas ventajas del bipedismo. (Ilustración de Karen Carr Studios)
Some advantatges of bipedalism. (Illustration by Karen Carr Studios)

DISADVANTAGES OF BIPEDALISM

  • Low speed: for short distances, running on two legs is slower than four, in case of an unexpected attack by a predator, the chance to escape decreases.
  • Back pain: the stress that suffers our spine and legs throughout life due to upright posture, is the most likely cause of back pain, knees, hips and feet that suffer a large part of the world population.
  • Birth complications: our birth canal is narrower due to the structure of our pelvis, plus the large size of the skull of the young, it causes more pain and complications in human births compared to other mammalian quadrupeds.
Canal del parto en una mujer (izquierda) y una chimpancé (derecha). Foto tomada de Jose Mª Bermúdez de Castro
Birth canal in a woman (left) and a chimpanzee (right). (Photo taken of Jose Mª Bermúdez de Castro)

Thus, despite the disadvantages, in a warm environment, rather arid and with few trees for shelter from predators, who survived were bipedal hominoids. We consider our bipedalism as a trait that makes us human, as it is unique among animals: only birds are fully bipedal -like some extinguished dinosaurs, and except the penguin -with clumsy gait, their spine is not perpendicular to the ground, like ours.

REFERENCES

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Lucy in the ground with diamonds

Surely one of the responsibles that you’re reading this post was the climate change that took place about 6 million years ago. The lifting of the Rift Valley caused a cooling and drying of sub-Saharan Africa, which favored the extension of the savannah at the expense of forests and the evolution of the first hominans who already walked by two feet. The most famous of them is undoubtedly Lucy. We encourage you to meet Australopithecus afarensis and the anatomy associated with bipedalism.

¿WHO WAS LUCY?

Just over 40 years ago, Donald Johanson discovered a partial skeleton (AL-288-1) 3.2 million old in Hadar, Ethiopia. It was the oldest hominan discovered and the bones belonged to an unknown species. At night, while celebrating the discovery with his team, the Beatles song Lucy in the Sky with Diamonds was playing in the cassette, and nicknamed the fossil remains. They belong to the species Australopithecus afarensis (Afar southern monkey).

Reproducción de Lucy del Museum national d'histoire naturelle, Paris. (Foto: autor desconocido, Wikimedia)
Cast of Lucy in the Museum National d'Histoire Naturelle, Paris. (Photo: unknown author, Wikimedia)

Currently A. afarensis is one of the best known early hominans, as it have been found remains of hundreds of individuals, males, females and young ones.

ANATOMY

The average height and weight of A. afarensis was 1.05 m and 29 kg for females and 1.51 m and 42 kg for males, significantly smaller compared to us. Brain volume was also small, 387-550 cubic cm (similar to a current chimpanzee). The arms and fingers were longer than ours, which allowed them to climb easily in the trees, and the legs, though shorter, had characteristics that allowed bipedalism (walking on two feet) completely. The forehead was narrow and jaws were located forward (prognathism), with a large space for jaw muscles. Their diet was mainly herbivorous.

Representación de Lucy por Elisabeth Daynès, con las huellas de Laetoli, en CosmoCaixa Barcelona. (Foto: Mireia Querol)
Reconstruction of Lucy by Elisabeth Daynès, with Laetoli footprint trails, in CosmoCaixa. (Photo: Mireia Querol)

ANATOMICAL FEATURES OF BIPEDALISM

A. afarensis already had the necessary adaptations to walk like us, though perhaps is not the older bipedal hominan: Orrorin tugenensis (6.2 to 5.6 million years) is aspiring to be one of the first members of the human race who walked upright .

skeleton comparison
Comparison between the skeletons of a current human (Homo sapiens), an A. afarensis and a chimpanzee (Pan troglodytes). (Photo: H. sapiens unknown author, A. afarensis John C. Phillips, chimpanzee Udo M. Savalli).
  • Foramen magnum: the spinal cord goes through an opening in the skull, the foramen magnum. In the chimpanzee is located in the back of the skull, while afarensis has it in the base, which allows a vertical backbone settle.
  • Backbone: lumbar and cervical area of the human backbone are more curved, we have a column with a S” shape. The center of gravity is in the midline of the foot and allows spinal flexion during walking, therefore when chimpanzees walk on two feet, stagger for balance because they have a straight spine.
  • Rib cage: A. afarensis still has a rather conical chest to accommodate a larger digestive system due to herviborous diet and better shoulder mobility to climb. H. sapiens have it shaped like a barrel, which facilitates the swing arm for better balance while walking and allows a better torso bending.
  • Pelvis: human pelvis is shorter and wider than other primates, to allow better mobility with the base of the backbone, but the birth canal is narrow.
  • Feet: A. afarensis toe, like ours, is aligned with the rest of the fingers, the sole is arched and a wide bead allows the foot to propel with the fingers and absorb shock when walking.
  • Femur: due to bipedalism the joint surface is wide and the femur is angled toward the center of gravity. In the chimpanzee femurs are shorter, less inclined and with lower joints.

LAETOLI FOOTPRINT TRAILS

Huellas de Laetoli, Tanzania. (Foto: Science Library)
Laetoli footprint trails, Tanzania. (Photo: Sciencephoto Library)

2.000 kms further south where Lucy was found, in Laetoli (Tanzania), Mary Leakey discovered in 1978 the oldest known biped trail (3.6 million years) of probably 4 hominans who walked through the open savannah, with traces of other extinct animals like the horse Hipparion, a bird, a baboon and a centipede. The tracks are laid down in the ashes of the volcano Sadiman and are attributed to A. afarensis. There are 69 footprints, some overlapping others intentionally, perhaps as a strategy to leave no trace. The big toe is parallel to the rest of the fingers and a deep footprint and the bead is well marked, which confirms a completely bipedal stride.

But why has it been so important bipedalism in the process of humanization, towards the emergence of Homo sapiens? We’ll find out in the next article on human evolution.

Representación de A. afarensis por John Gurche. (Foto: Chip Clark)

Rreconstruction of A. afarensis by John Gurche. (Photo: Chip Clark)

 

REFERENCES

If you enjoyed this article, please share it on social networks to spread it. The aim of the blog, after all, is to spread science and reach as many people as possible.

This publication is licensed under a Creative Commons:Llicència Creative Commons

Licencia Creative Commons Atribución-NoComercial-CompartirIgual 4.0 Internacional.