Gaudin, T.J. (1 February 2004). "Phylogenetic relationships among sloths (Mammalia, Xenarthra, Tardigrada): the craniodental evidence". Zoological Journal of the Linnean Society. 140 (2): 255–305. doi: 10.1111/j.1096-3642.2003.00100.x. ISSN 0024-4082. Monge Nájera, J. (2021). Why sloths defecate on the ground: rejection of the mutualistic model. UNED Research Journal, 13(1), 4-4. The pale- and brown-throated three-toed sloths mate seasonally, while the maned three-toed sloth breeds at any time of the year. The reproduction of pygmy three-toed sloths is currently unknown. Litters are of one newborn only, after six months' gestation for three-toed, and 12 months' for two-toed. Newborns stay with their mother for about five months. In some cases, young sloths die from a fall indirectly because the mothers prove unwilling to leave the safety of the trees to retrieve the young. [53] Females normally bear one baby every year, but sometimes sloths' low level of movement actually keeps females from finding males for longer than one year. [54] Sloths are not particularly sexually dimorphic and several zoos have received sloths of the wrong sex. [55] [56]

Svartman, Marta; Stone, Gary; Stanyon, Roscoe (21 July 2006). "The Ancestral Eutherian Karyotype Is Present in Xenarthra". PLOS Genetics. 2 (7): e109. doi: 10.1371/journal.pgen.0020109. ISSN 1553-7404. PMC 1513266. PMID 16848642. {{ cite journal}}: CS1 maint: unflagged free DOI ( link) Southern two-toed sloth". Smithsonian's National Zoo. 25 April 2016. Archived from the original on 17 July 2019 . Retrieved 30 October 2019. Three-toed sloths go to the ground to urinate and defecate about once a week, digging a hole and covering it afterwards. They go to the same spot each time and are vulnerable to predation while doing so. Considering the large energy expenditure and dangers involved in the journey to the ground, this behaviour has been described as a mystery. [49] [50] [51] Recent research shows that moths, which live in the sloth's fur, lay eggs in the sloth's feces. When they hatch, the larvae feed on the feces, and when mature fly up onto the sloth above. These moths may have a symbiotic relationship with sloths, as they live in the fur and promote growth of algae, which the sloths eat. [5] Individual sloths tend to spend the bulk of their time feeding on a single "modal" tree; by burying their excreta near the trunk of that tree, they may also help nourish it. [52] Reproduction Soares, C. A.; Carneiro, R. S. (1 May 2002). "Social behavior between mothers × young of sloths Bradypus variegatus SCHINZ, 1825 (Xenarthra: Bradypodidae)". Brazilian Journal of Biology. 62 (2): 249–252. doi: 10.1590/S1519-69842002000200008. ISSN 1519-6984. PMID 12489397.

Wild brown-throated three-toed sloths sleep on average 9.6 hours a day. [37] Two-toed sloths are nocturnal. [38] Three-toed sloths are mostly nocturnal, but can be active in the day. They spend 90 per cent of their time motionless. [24] Behavior Thank you for allowing us to respond to this review by Sander Gilman whose work we have admired and enjoyed. Goffart, M. (1971). "Function and Form in the sloth". International Series of Monographs in Pure and Applied Biology. 34: 94–95. Sloths have an uncommonly slow metabolism. When a sloth eats, the time its body takes to convert that food source into energy is far longer than the average mammal of its size. Because of this and their low-calorie diet of leaves, sloths are always low on energy, so they need to be conservative in how they use it. They move slowly, stay within a small home range, and only relieve themselves once a week. Liberg, O. (1980). Spacing patterns in a population of rural free roaming domestic cats. Oikos, 32(3),336-349.

The result of infection since over the past 20 years six different pathogens have been reported to cause obesity in animal models as well as humans. Pauli, Jonathan N.; Mendoza, Jorge E.; Steffan, Shawn A.; Carey, Cayelan C.; Weimer, Paul J.; Peery, M. Zachariah (7 March 2014). "A syndrome of mutualism reinforces the lifestyle of a sloth". Proceedings of the Royal Society. The Royal Society Publishing. 281 (1778). The main reason for a sloth’s lethargic movement is its specialised metabolism. They live off low-calorie vegetation that their bodies turn into energy at a very slow speed. Their metabolic rate is about 40-45% of the average speed expected in a mammal their size, and it can take anywhere from 157 to 1,200 hours for a sloth to metabolise and excrete a leaf it eats. There are six species of sloth, all with their own scientific names. They were previously all classified under the family Bradypodidae, but later research showed so many differences between two-toed and three-toed sloths that the two-toed sloths were given their own family, Megalonychidae. Scientists have determined that there are four distinct species of three-toed sloths and two distinct species of their two-toed cousins. Here are their scientific names: There are six extant sloth species in two genera – Bradypus (three–toed sloths) and Choloepus (two–toed sloths). Despite this traditional naming, all sloths have three toes on each rear limb-- although two-toed sloths have only two digits on each forelimb. [3] The two groups of sloths are from different, distantly related families, and are thought to have evolved their morphology via parallel evolution from terrestrial ancestors. Besides the extant species, many species of ground sloths ranging up to the size of elephants (like Megatherium) inhabited both North and South America during the Pleistocene Epoch. However, they became extinct during the Quaternary extinction event around 12,000 years ago, along with most large bodied animals in the New World. The extinction correlates in time with the arrival of humans, but climate change has also been suggested to have contributed. Members of an endemic radiation of Caribbean sloths also formerly lived in the Greater Antilles but became extinct after humans settled the archipelago in the mid-Holocene, around 6,000 years ago.a b Pauli, J. N., Mendoza, J. E., Steffan, S. A., Carey, C. C., Weimer, P. J., & Peery, M. Z. (2014). A syndrome of mutualism reinforces the lifestyle of a sloth. Proceedings of the Royal Society B: Biological Sciences, 281(1778), 20133006. DOI: 10.1098/rspb.2013.3006 The IUCN Red List currently categorises four of the sloth species as least concern, one species as vulnerable, and one species as critically endangered—the pygmy three-toed sloth. The maned three-toed sloth was previously listed as endangered because their range was thought to be very restricted. However, new data found more areas where this species lives, and they were recategorized as vulnerable. As I noted this is a comprehensive study of BOTH ‘medical’ and ‘cultural’ representations of obesity, which makes the problem of the volume even more engaging. The notion that representations validate medical views seems very 19th century, very much enmeshed in a Rankian positivism rarely seen today in studies of medical imagery. Yet the study is sophisticated enough to engage in a rather good summary of the ideological meanings grafted onto to the constructed categories of obesity over the ages. But in its analysis of medicine remains a sphere seemingly devoid of ideology. Thus the representation of medical knowledge is one that centers on the ‘facts’ of contemporary medicine and their antecedents. That there are recent approaches to obesity that are no longer seen as ‘scientific,’ such as the psychoanalytic ones proposed by Hilde Bruch in the 1950s, is ignored. But of course in the 1950s these approaches assumed that they were the cutting-edge scientific explanation – and they were! Such claims of science as a true representation of the world, rather than a flawed or partial one, seem to be inherent to the science of obesity itself. And yet as indicated by my list above, even the medical authorities of our day seem not quite clear as to what obesity is and what its implications are. Do we assume that we are a fat collecting species? Do we assume that we are an addictive species? Is this not an inherent contradiction: if collecting fat is natural because it is preprogrammed in us genetically due to evolutionary processes how can it be pathological? How can an addiction to food be anything but natural and therefore non-addictive? a b c Alina Bradford (26 November 2018). "Sloths: The World's Slowest Mammals". Live Science. Archived from the original on 4 December 2020 . Retrieved 22 November 2020. Amson, E.; Muizon, C. de; Laurin, M.; Argot, C.; Buffrénil, V. de (2014). "Gradual adaptation of bone structure to aquatic lifestyle in extinct sloths from Peru". Proceedings of the Royal Society B: Biological Sciences. 281 (1782): 20140192. doi: 10.1098/rspb.2014.0192. PMC 3973278. PMID 24621950.