Media outlets can perpetuate these beliefs and keep them alive for decades. But, sometimes, members of those communities perpetuate them on their own.
There are, in fact, certain stereotypes about the black community that are believed and passed down, not by outsiders, but by folks within the black community itself.
Is there a such thing as "the itis"? Does black ever "crack"? Does a large group of black people generate a lot of heat? Are black people born with rhythm? Are black people naturally more athletic than other races? Do black men really have larger penises than other men?
Read further to find out which self-perpetuating characteristics of the black community are facts and which are fiction.
Black folks get "the itis" after eating
Short for the less palatable term "ni**eritis," the term is used in both the United States and Caribbean to describe the routine of becoming sleepy after eating a large meal. "The itis" is jokingly said to affect blacks more than any other group. The term also implies that the person who has "the itis" is lazy, and often too fatigued to return to work after their mid-day meal.
So is it fact or fiction?
"All of us are sleepier during early to mid-afternoon," says Dr. Mark Mahowald, former director of the Sleep Disorders Center at Hennepin Medical Center, and now a professor of neurology at University of Minnesota Medical School. "There is no racial difference in the sleepiness we all experience."
Most humans have their body clocks set to become sleepier between midnight and 6:00 am, and again around noon. Many people erroneously attribute this mid-day sleepiness to their big lunch, sitting in a dark room, hot weather, or a boring meeting.
However, these things do not cause sleepiness or "the itis," they simply bring out the mild sleepiness that was already there from their intrinsic body clocks.
"This is why cultures wiser than ours have picked that time for their siesta [or nap] time," says Mahowald.
Small studies have shown increased sleepiness after eating meals high in carbohydrates or high in fats, but others show no effect.
So where did the "itis" notion come from?
One theory is that, given the predisposition for sleepiness during those times, that any group of people that are also exposed to the heat after eating a large lunch, without taking a nap is set up for "the itis," so to speak, says Mahowald.
The fact that both now, and decades ago, blacks in the United States and the Caribbean have been overrepresented in outdoors work during warmer climates, makes this theory a strong possibility.
In a subset of African-Americans, a condition called obstructive sleep apnea could play a role. Overall, it tends to affect people who are obese, but African-Americans are more affected despite body habitus. People with obstructive sleep apnea stop breathing several times during sleep, for seconds at a time, usually due to obstruction from the tongue, fat around the neck, or in the case of many African-Americans, the natural construct of their airways - the nose, throat or adenoids. Because of the lack of restful sleep, people with this condition are often sleepy during the day. This also increases the risk of decreased alertness in the setting of the other factors already mentioned.
Conclusion: Since all people technically get "the itis," the myth is somewhat true. But, since it doesn't affect blacks more than other groups as the stereotype says, that makes it fiction.
Black Don't Crack
The popular belief that people of African descent look younger than their stated age is what sits behind the quip, "black don't crack."
Numerous black celebrities have aged gracefully over the years, including singer Lena Horne who died last year at 92, 45-year-old actor Blair Underwood, and 45-year-old actress Stacey Dash who still convincingly plays 20- and 30-something characters. Many black families have their own personal stories of ageless beauty to tell.
So, is it fact or fiction?
"In my dermatology practice, black men and women tend to present with skin aging concerns about a decade later than my patients with lighter skin," says Dr. Andrew F. Alexis, director of the Skin of Color Center at St. Luke's Roosevelt Hospital in New York City.
The types of complaints are also different, Alexis says. Aging black men and women often seek treatment for uneven skin tone, large pores or moles. Yet, the leading cosmetic concerns in his aging Caucasian patients involve fine lines, wrinkles and other signs of sun damage.
Melanin, a pigment that affects the color of hair, eyes and - most importantly - skin, serves as natural sun protection. Since ultraviolet radiation from the sun causes skin to age faster, darker skin is more protected from those changes. People with fairer skin who did not use sunscreen at a young age are thus exposed to decades of sun damage long before reaching their older years.
However, the sun can still damage darker skin, and in addition to cosmetic changes, people with darker skin can develop skin cancer. So, even though "black don't crack," staying out of the sun, using a hat or umbrella to block sunrays, wearing sunscreen and avoiding cigarette smoking can stave off the cracks for a few years longer.
Black folks generate more heat
The clichéd scenario is a room filled with black people, where the room then becomes uncomfortably hot and someone frustratingly calls out, "There are too many black people in here," as he or she escapes the room. Said person is usually referring to the concept that a group of black people generates more heat than other races. And, thus requires areas with more aeration or simply not gathering so closely together or so numerously.
So is it fact or fiction?
"The amount of heat radiated can depend on a handful of factors - race does not appear to be one of them," says Dr. David Keller, assistant professor in the Department of Kinesiology at the University of Texas, who regularly performs research on how the body regulates its own temperature.
People with larger body size, for example, tend to radiate more heat than those who are smaller, he says. Yet, no studies have shown a significant difference merely based on race.
Researchers in North Carolina recorded the body temperatures of nearly 100 elderly volunteers and found that black women had higher readings than the white women in the study -- 98.5 degrees compared to 98.3. No difference was seen between black men and their white counterparts. The study was too small to draw larger conclusions.
All humans radiate heat throughout life, Keller explains. As the body's temperature changes, so does its need to release heat. Temperatures can change throughout the day, even at rest, but most people -- regardless of race -- remain within the same narrow range.
Since black objects, like clothing, absorb the sun's heat more intensely, older theories have implied that darker skin would also absorb more heat. However, in a lecture on heat transfer at the University of Houston, Engineering Professor Dr. John Lienhard confirmed that there is no difference: Dark skin absorbs no more heat than light skin does.
Black people are born with natural rhythm
When one sees the prevalence of African-Americans in the music and dance industries, it can easily appear as though black people do have natural rhythm. In a nightclub or simply while listening to music, it is common to find people of African descent moving to the beat of the music in a way that appears innate. If a black person doesn't have rhythm, it is a cause for shame or, potentially, a reference to "dancing like a white person."
So is it fact or fiction?
If black people have innate rhythm, it is likely because of environment, not birth, says Dr. Andrée Grau, professor of the anthropology of dance at the University of Roehampton in London.
Children are often exposed to music and rhythm unknowingly. A child carried by his or her mother, as an infant, while she works around the house, or dances and sings to herself will have an experience different from a child who is not, says Grau. In certain cultures, this exposure continues at events such as parties, church services and theatrical events.
In cultures of Sub-Saharan African descent, the music is often polyrhythmic, forcing different body parts to move uniquely to different rhythms in dance.
It is also known that children who have early access to dance and music are more likely to be better at both later in life than those who wait until adolescence.
This is in line with the debated concept that race is cultural rather than biological.
British psychologist Richard Lynn argues that the stereotype is fiction altogether. In his 2006 book, Race Differences in Intelligence, Lynn compares the IQs of African-Americans to those of European descent with respect to musicality -- tone, pitch, music memory, chord analysis -- as well as rhythm.
African-Americans scored higher on the rhythm portions compared to musicality, but there was no difference in rhythm IQs between them and the Europeans tested. This suggests that both cultures have the same capacity for rhythm.
However, studies of identical and fraternal twins suggest that musical ability has a genetic component, raising the question of whether rhythm is also affected by genetics.
Grau is still not convinced it's genetic. "It is easy for people to assume that because participating in dance is not a choice [in many African societies] and often an unavoidable social duty, and as a result, everyone is at least an adequate performer, these people must have dance 'in the blood,' especially when compared to some 'two left-footed' Europeans!"
She adds that even in ballet, usually dominated by non-blacks, certain techniques require fast footwork and body isolation similar to polyrhythmic dance. Yet, they are able to master those exercises without difficulty, despite not being of Sub-Saharan descent.
Conclusion: There are more sound explanations for why rhythm is a learned skill rather genetically based. The verdict is still out, but this seems to be more on the side of fiction.
Black men are naturally athletic
More than 80 percent of the National Basketball Association and over 60 percent of the National Football League are made up of black players. Blacks hold every major running record in the world, according to Jon Entine in an article about why race matters in sports. He adds boxing to the list of sports black men dominate as well.
One theory is that black men are just naturally athletic, and can dominate most sports without additional effort.
Is this fact or fiction?
Fact, depending on the sport.
Through research on his book, Taboo: Why Black Athletes Dominate Sports and Why We're Afraid to Talk About It, and collaboration with experts on the topic, Entine makes the case that it is less about race and more about environment and ethnicity.
In the book, he explains the athletic features of particular ethnic groups:
People of West-African descent are superior in speed and jumping. With more fast-twitch fibers than other groups, muscles can contract faster and more powerfully. The athletes' small, efficient lungs lend itself to sprinting as well.
"The best whites and Asians cannot jump as high as elite African-American athletes," Entine says.
However, these characteristics make athletes of West-African descent less effective at endurance sports, and with their lower body fat, less buoyant when swimming.
On the other hand, East Africans win more than half of the top endurance races, and have more slow-twitch fibers, which contract for longer periods of time, and have lung capacities and a metabolism for longer races.
Whites of Eurasian backgrounds have more upper body strength and dominate in weight lifting and shotput.
And, East Asians excel at diving, ice skating and gymnastics due to an inherent predisposition for flexibility.
Black anthropologist William Montague Cobb suggested in 1939 that black Americans are physically superior due to the difficult physical trials throughout history in order to survive as a population.
"From this standpoint [the Negro] is the most highly selected stock in America... physically strong, showing great endurance at strenuous labor under severe climactic and nutritional hardships and producing a disproportionately large number of champions in representative fields of athletics."
Conclusion: While black men dominate certain sports, namely basketball, football, boxing and track, Entine points out that whites still dominate the majority of athletics, especially winter sports. So, it is fact that black men are genetically programmed to excel in those specific sports. However, this fact is not generalizable to all sports.
Black men are well endowed
If hearsay and the images perpetuated in the pornography industry are true: black men are more endowed than men of other races.
Is it a fact?
If so, the difference in size is not huge.
There are extremes in size across every race -- extremely short penises, called micropenises, and extremely long ones. But, overall, most men fall close to the average lengths, ranging between 5.5 inches and 6.3 inches. The Kinsey Data suggest that black men have similar lengths as white men or, if larger, just slightly and insignificantly so. Asian men, however, consistently measure shorter than both white and black men in various literature.
In line with that finding, the Indian Council of Medical Research measured 1,200 men and found that 60 percent were too small for the international standard size for condoms.
Six years ago, on the other hand, after South African men complained that the government standard condoms were too small, condom maker Durex created and ship special extra large condoms to the country.
Incorrectly fitting condoms is an important factor in condom failure worldwide.
As a result, the World Health Organization created size guidelines for the condoms shipped to certain regions.
These measurements are based on three studies that indicate that African men require slightly longer and wider condoms, Caucasian men require medium condoms and Asian men require shorter and slightly narrower condoms.
In a study on condom fit among African-American men who have sex with men, 1 in 5 felt the condoms were too tight, 1 in 5 felt the condoms were too short. Only 1 in 10 felt the condoms were too loose. But, the actual lengths and girths were not measured.
Not all studies support such large measurements in African men, however. A study of Nigerian men in 1985 measured over 300 men age 17 to 23 and found the average length of a flaccid penis to be 3.47 inches, which is almost one inch shorter than the average flaccid length.
If one were to ignore the previous Nigerian study and assume that the hypothesis that African men have larger penises is true, it still does not necessarily translate to African-American men. The common mixtures of Caucasian, African and Native American in African-American families, as well as the addition of other ethnicities and races such as Asian populations ultimately brings the measurements closer to the average, experts say.
If this stereotype is not conclusively factual, where did it come from?
Herbert Samuels, professor at LaGuardia Community College in New York writes that this stereotype is likely linked to the opinions of 16th century West Africa that described black men and women as bestial, animalistic and hypersexual. This description also included the black man as a "sexual superman" with a penis larger than the white man and increased potency.
In the present day, Samuels describes, African-American men may perpetuate their own stereotype, since it is a rare time when a stereotype about them is not drastically negative. In some ways, it has become a sense of the black male identity.
Conclusion: Perhaps among African men, there is a slight difference in size, but among African-American men, this stereotype is likely fiction and rooted more in racist, historical rhetoric.