Category Archives: Biology

How many gallons of human blood are there?

For this we need to know how many people there are and the average amount of blood in each one. Unfortunately, I will be assuming that all humans are adult sized with an adult amount of blood, which I’m fairly sure is not the case, so the estimated value will be higher than the actual value by a fairly substantial amount.
Now then. As of January 3rd, 2014, the date which this was written, the Worldometers world population clock [1] put the total world population at about 7.204 billion people.
As for blood, hypertextbook [2] cites several scientific studies which have found that the amount of blood in the average adult is right around 5 liters (or about 5 quarts). This means that the average person has about 1.25 gallons of blood.
By multiplying the two results we find that the total amount of human blood is right around 9 billion gallons.
Using data from a 2010 Pew poll of world religions [3] we find that there are 2.8 billion gallons of Christian blood, 2.1 billion gallons of Muslim blood, 1.4 gallons of Hindu blood and only 18 million gallons of Jewish blood. (These numbers don’t add up to the total because of other religions and the 1.5 gallons of unaffiliated blood)

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Filed under Biology, Mathematics, Religion

Sildenafil

Sildenafil (other uncommon names: 1-[4-ethoxy-3-(6,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-5-yl)phenylsulfonyl]-4-methylpiperazine, or C22H30N6O4S) is a common prescription drug originally synthesized by a group at the Pfizer’s facility in Sandwich, Kent, UK for use as a hypertension and heart disease drug, however, clinical trials found little impact on heart disease. It does however work well for treatment of a specific type of hypertension called pulmonary hypertension as well as altitude sickness, which may be experienced by mountain climbers and pilots, and another disorder. Some rare but serious side effects of sildenafil include stroke, heart attack, hypotension, and sudden hearing loss. Although illegal to use without a prescription, there is recreational use of sildenafil which is not diminished by the drug’s brand name and notoriety. Finally, the 2007 Ig Nobel Prize (not to be confused with the Nobel Prize) in Aviation went to an Argentinian team who discovered that sildenafil positively impacted how quickly hamsters recover from jet lag. Bonus points if you can guess the brand name of sildenafil (no cheating).

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Nature’s Bad@$$es: The Pen-Tailed Treeshrew

I’m changing the “Historical Bad@$$” series to the “Bad@$$es” category, which will also include different species of animals.

Like many treeshrews, the pen-tailed treeshrew has a high brain-to-body mass ratio, but unlike other treeshrews, it is nocturnal. Also, its diet consists mainly of alcohol. The pen-tailed treeshrew spends several hours each night drinking fermented nectar from the bertam palm tree equivalent to 10-12 wine glasses of 3.8% alcohol. The pen-tailed treeshrew does not get intoxicated, despite alcohol levels that would affect humans, because they make extensive use of an alcohol metabolism pathway not highly used in humans.

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Filed under Bad@$$es, Biology, Science

Lengthy Post: Races, Historical and Modern

Race, a controversial topic, has been the reason for hate crime, genocide, discrimination, disenfranchisement and other atrocities. But what is race really? Race appears to be a human method for classifying other groups of humans, distinguishing “us” from “them”. Most determinants of race are outward physical traits, namely facial features, build and skin color. The last feature, skin color, is a prominent distinguishing feature of the races, which have been separated in color groups. Historically, the Caucasian peoples have been associated with white, East Asian peoples with yellow, North African, Middle Eastern and South Asian peoples with brown, Sub-Saharan and Australian Aboriginal peoples with black and Amerindian peoples with red. Still another racial definition is based on ancestral homelands. Caucasian people from Europe, North Africa, the Horn of Africa, the Middle East and Central and South Asia, Negroid people (these are historical terms, you can expect racism) from Sub-Saharan Africa and Australia, Mongoloid people from East, South East, North, and Central Asia, the Americas, the Arctic and some Pacific islands. Recent genetic research has uncovered some evidence of separate races, but based on adaptations to a homeland while retaining inter-race breeding capability (every different race is still part of the same species). A 1994 study set up 9 potential races: African, New Guinean & Australian, Pacific Islander, Southeast Asian, Amerindian, Arctic Northeast Asian, Northeast Asian, European Caucasoid and Non-European Caucasoid. Racial studies continue to be controversial, but perhaps through studying race we might learn it doesn’t exist.

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Filed under Biology, Culture, Science

Double Post From the Archives: Sharks (August 14 & 15)

Sharks are arguably the oldest family of large animals still alive, with the oldest accepted shark fossil being about 420 million years old, predating the dinosaurs, land animals, and even land plantlife. Sharks as a group have survived four major mass extinctions, each of which had killed at least 70% of all species then living on the planet. Sharks have a great sense of smell, able to detect blood in a concentration of one part per million (for every drop of blood, there are 1 million drops of water), and they have another sense called electroreception, which allows them to detect Earth’s magnetic field…and any movement of nearby prey. Only four shark species (great white, tiger, bull and oceanic whitetip) produce a significant number of fatal shark attacks. Sharks in general, and those four in particular, are the top predators of their environment, and like many other natural hunters, are curious of unfamiliar creatures (read: humans). However, they lack any means to explore the unknown other than their mouth, which can explain some shark attacks considering humans are generally not sufficient prey to warrant feeding as a reason to attack. On average, there is less than one death from a shark attack each year while there are, on average, forty deaths from lightning strike. Finally, the eggs of the grey nurse shark hatch inside the mother and when the first embryo develops, it eats its sibling’s embryos and any unhatched eggs. Talk about sibling rivalry.

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Filed under Biology, From the Archives, Science

Chromosomes

Chromosomes. Everyone has them, every living thing with a nuclei in their cells has them. Every plant, every animal, every fungus and a selection of microbes has/have chromosomes. Basically, all of the genetic information of an organism with chromosomes is stored in the chromosomes (except mitochondrial DNA, but that’s weird stuff and is arguably not part of the organism’s genome) which, during cell division, bunch up and double up so they look like tiny, fat X’s. Many organisms have an even number of chromosomes, largely due to the nature of sexual reproduction, which requires an even number of chromosomes to form sex cells, but the range of the number of chromosomes any organism has varies widely based on species. For example, humans have 46 chromosomes, the same as the Reeves’s muntjac and Sable antelope. wolves, jackals, dogs and chickens all have 78 chromosomes, shrimp and two rat species have around 92, gypsy moths and giraffes both have 62, zebrafish and rice have the same number of chromosomes, 24. The organism with the most chromosomes is the Adders-tongue plant, with over 1,000 chromosomes (one Wikipedia page says 1440, another says 1262, so I’m just being vague), and the organism with the least chromosomes (not counting those without them) is the male Jack jumper ant, which has a single chromosome due to ant sexual behaviors (female jumper ants have a normal number of chromosomes for their species, 2).

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Carnivorous Plants Part 2: Snappers, Bladders and Lobster-pots

Snapping traps are most commonly associated with the famous Venus flytrap, which quickly closes in response to a trigger hair being touched, however there is another plant, the waterwheel plant, which closes its feeding parts when triggered by aquatic prey. After the trap is closed and the prey contained the plant releases its digestive fluid. Bladder trap plants pump ions out of their bladders, which causes water to also leave the bladders, creating a partial vacuum. Trigger hairs alert the plant to nearby prey and cause the bladders to open up. The flow created by the bladder opening pulls prey into the bladder where it is digested. Finally, lobster-pot trap plants use small hairs inside specialized leaves to easily allow prey in, but not out. Water flow in the trap may encourage prey to continue toward their doom,  a stomach-like region of the leaf where the prey is dissolved.

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Filed under Biology, Botany, Science