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June 8

Why are human testicles descended at birth, compared to weeks later for other mammals?

Why is it that human infant's testicles are descended at birth, whereas in many mammals this does not occur for weeks if not months after birth. Is there some sort of biological significances to this? Or is it more of a anatomical quirk.109.62.221.215 (talk) 10:16, 8 June 2015 (UTC)[reply]

Here is some background information the questioner may already familiar with. Testicle#Development (discussing human development) says: Testes follow the "path of descent" from high in the posterior fetal abdomen to the inguinal ring and beyond to the inguinal canal and into the scrotum. In most cases (97% full-term, 70% preterm), both testes have descended by birth. In most other cases, only one testis fails to descend (cryptorchidism) and that will probably express itself within a year.

Cryptorchidism#Veterinary occurrence says: Dog testes usually descend by ten days of age and it is considered to be cryptorchidism if they do not descend by the age of eight weeks. and discussing cats: Normally the testicles are in the scrotum by the age of six to eight weeks.

I did learn that adult elephants have intra-abdominal testes, and this is taken as a relict of their aquatic past, but I'm not sure where to find information about the age for testicular descent with other animals in order to verify the premise of this question. -- ToE 13:04, 8 June 2015 (UTC)[reply]

I don't have a source, but IIRC, I believe elephants have a lower body temperature than the average placental mammal, hence no need for external testicles to keep them cool enough to produce sperm. μηδείς (talk) 18:33, 8 June 2015 (UTC)[reply]

Interesting. From CRC Handbook of Marine Mammal Medicine Pg 153: "Ascrotal testes are typical for many marine mammals, such as phocid seals, dolphins, and manatees. There are vascular adaptations that prevent deep-body hyperthermic insult in cetaceans and phocids. In dolphins, cooled venous blood is delivered to an inguinal counter-current heat exchanger to cool the testes and epididymides indirectly, whereas, in phocid seals, cooled venous blood is delivered to an inguinal venous plexus to cool the testes and epididymides directly." I would have assumed that elephants had something similar.

In any case, I thought that there might be a relation to gestation period and looked into elephants as an extreme example, but I can't find enough information about various animals to even decide if the premise that prenatal testicular descent is atypical in non-human animals is correct, though I did run into many sources which said that the mechanism regulating it in humans is not fully understood. -- ToE 20:29, 8 June 2015 (UTC)[reply]

Here's some relevant info on elephants: http://www.publish.csiro.au/?act=view_file&file_id=SRB03Ab59.pdf --82.164.37.199 (talk) 20:41, 8 June 2015 (UTC)[reply]

Thanks. Supporting that, Biology, Medicine, and Surgery of Elephants Pg. 353: "Elephant testes are unique because there is no pampiniform plexus to assist in cooling the testes below body temperature. However, the normal body temperature in elephants is 34-36°C which is about the temperature at which the testes of scrotal mammals are maintained." +1 Medeis, but still no answer for the original question yet. -- ToE 20:54, 8 June 2015 (UTC)[reply]

Footballers with mohawks

Watching the Champions League final on Saturday night it seemed to me that a higher than average percentage of the players were sporting mohawks. How long has this been a thing for? Was Mario Balotelli the instigator of the trend, or were there other examples before him? --Viennese Waltz 12:26, 8 June 2015 (UTC)[reply]

David Beckham had one in 2001 [1] when Balotelli was 11 by my count. Those of us old enough to remember the 1970s still call it a Mohican, since the haircut was originally inspired by a BBC TV drama. Alansplodge (talk) 22:29, 8 June 2015 (UTC)[reply]

See the fauxhawk, which has been around for the last decade or so. μηδείς (talk) 23:23, 8 June 2015 (UTC)[reply]

Actually, the hairstyle (as worn by white folks) is much older than the 1970s as it dates back to World War II and the 101st Airborne Division [2] [3]. The show mentioned by Alanssplodge may have helped to resuscitate its popularity among British Punk music fans in the late 1970s however. --Xuxl (talk) 11:31, 9 June 2015 (UTC)[reply]

Rape

In England are murders and rapists allowed to represent themselves in court and cross-examine the victim? — Preceding unsigned comment added by 202.118.236.130 (talk) 15:03, 8 June 2015 (UTC)[reply]

Does English law have the presumption of innocence? ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:44, 8 June 2015 (UTC)[reply]

Cross-examination of murder victims is uncommon in England. 95.103.249.248 (talk) 15:47, 8 June 2015 (UTC)[reply]

I will guess at what User:Baseball Bugs meant by his question. It may have implied that the original question was wrongly worded, in referring to "murders" (sic) and rapists. It should probably have referred to persons charged with murder and rape. Common law, in England, the United States, and elsewhere, assumes that the defendant is innocent until proved guilty. (So does civil law, but that isn't relevant here.) Robert McClenon (talk) 15:56, 8 June 2015 (UTC)[reply]

No need to protect theoretical people, though. Whatever they're presumed, many actual people charged with murder are there for having murdered someone. Any answer to what they can do in court applies to non-murderers charged with murder. If guilty people were given different rules at trial, there'd be no need to try them. That would be more literally prejudicial than calling them all criminals would. But yeah, I digress. InedibleHulk (talk) 17:30, 8 June 2015 (UTC)[reply]

Cross-examination of rape victims is common and unpleasant. Cross-examination of murder victims may be considered to be either impossible or forbidden, depending on one's religion. Robert McClenon (talk) 16:37, 8 June 2015 (UTC)[reply]

The answer to the question in respect of rapists is NO: Youth Justice and Criminal Evidence Act 1999 Section 34: "No person charged with a sexual offence may in any criminal proceedings cross-examine in person a witness who is the complainant, either— (a) in connection with that offence, or (b) in connection with any other offence (of whatever nature) with which that person is charged in the proceedings". Alansplodge (talk) 20:32, 8 June 2015 (UTC)[reply]

To expand on the practical consequences of that provision, if a person charged with rape (or another sexual offence) is representing himself or herself at trial, the cross-examination of the complainant is carried out by an advocate paid for by the state. That advocate will speak to the defendant in order to understand their case (and therefore decide what questions need to be put to the complainant), but is not instructed by them or bound by their wishes in the same way as a normal defence advocate would be. Proteus (Talk) 11:33, 9 June 2015 (UTC)[reply]

Here's a general overview of victim and witness rights in the UK. Seems relevant enough. InedibleHulk (talk) 16:26, 9 June 2015 (UTC)[reply]

Rabies vaccionation after having contact with a bat?

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis, prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the Reference Desk's talk page.

Astroid 1860s

I am trying to research a threat of an astroid that was forecasted to hit earth in the month of June sometime in the 1860's, At the time the astronomers believed that this will destroy the world. I would appreciate it if anyone can help me find an exact date or any other information on this event?66.128.9.7 (talk) 18:28, 8 June 2015 (UTC)[reply]

The correct spelling is asteroid, which will help a bit. Is it possible you are thinking of the presumed disaster of us passing through Halley's Comet's tail in 1910? μηδείς (talk) 18:39, 8 June 2015 (UTC)[reply]

Are you perhaps thinking of the July 20, 1860 Great Meteor? (Though there were no predictions associated with this as far as I know.) -- ToE 20:41, 8 June 2015 (UTC) Astroid: (x,y)=(cos³(θ), sin³(θ)).[reply]

Nappy, coily or kinky hair

Ethnic groups that live near or south of the equator in Africa have kinky, coily or nappy hair, however, equatorial ethnicities outside Africa don't. Why did hair development differ so significantly? 2.96.211.51 (talk) 20:20, 8 June 2015 (UTC)[reply]

Our article is Afro-textured hair with the section Afro-textured hair#Evolution touching on your question. -- ToE 20:34, 8 June 2015 (UTC)[reply]

(EC) The current understanding is that all human hair started out like that of Africans (just like all humans started out with dark skin) - it's the straighter, lighter hair (and paler skin) that was later derived in other populations, to adapt to different environmental conditions. It basically works out the same as the dark skin - Afro hair is probably better and more comfortable/protective in hot/humid climates than e.g. straight blond hair. See Afro-textured_hair#Evolution, and Hair#texture for additional discussion and references. SemanticMantis (talk) 20:35, 8 June 2015 (UTC)[reply]

It's also worth pointing out that this hair type does occur in "equatorial ethnicities outside Africa". The article section linked above mentions specifically Polynesians, Micronesians, Melanesians, Australoids and the Negrito.--William Thweatt ^Talk^Contribs 04:08, 9 June 2015 (UTC)[reply]