• When and how did scientists come to conclusion that all humans originated in Africa?

    Best answer: 1. The earliest known modern human (H. sapiens) fossils are found in Africa, dated to about 150,000 to 200,000 years old. 2. Mitochondrial DNA data suggests that "Mitochondrial Eve" is an African. We determine that by comparing the mtDNA of females from different places on earth. The descendant of the... show more
    Best answer: 1. The earliest known modern human (H. sapiens) fossils are found in Africa, dated to about 150,000 to 200,000 years old.

    2. Mitochondrial DNA data suggests that "Mitochondrial Eve" is an African. We determine that by comparing the mtDNA of females from different places on earth. The descendant of the oldest population should have a genetic marker that is shared by all other women, but other women, because they migrated out of Africa, would not have some of the DNA markers that an African woman may have. They also have DNA markers that they share with other non-Africans but not found in Africans. Therefore by determining which markers are the oldest one and which of them are newer ones and are found only in some places but not others, scientists determined that women originated in Africa.

    3. Y chromosomes are inherited from the father by the son. By comparing Y chromosomes using the same method as we did on mitochondrial DNA (which are transmitted from mother to son and daughter but not from father to son or daughter), we also determined that the first male human originated from Africa

    DNA sequencing was too slow before the 1990s, although mitochondrial DNA could be analyzed earlier. Since mtDNA, Y chromosome and fossil data all support the theory that humans originated in Africa, it is now widely held by most people, except perhaps racists who would not accept the idea that their ancestors could have been an African 60,000-70,000 years ago.
    20 answers · 2 days ago
  • Do primates bury their dead?

    What do they do?
    What do they do?
    9 answers · 3 days ago
  • Why are cougars much less aggressive toward humans than leopards?

    Best answer: I grew up in cougar country in the Black Hills of South Dakota but I have only seen their tracks there. South Dakotans often have guns and cougars there are extremely cautious of humans. Here in Southern California on the other hand, I have seen two and heard one very close. One that I saw was facing down a guy... show more
    Best answer: I grew up in cougar country in the Black Hills of South Dakota but I have only seen their tracks there. South Dakotans often have guns and cougars there are extremely cautious of humans. Here in Southern California on the other hand, I have seen two and heard one very close. One that I saw was facing down a guy as I was running down a trail. I thought it was his golden retriever that I saw run off into the brush but the guy was so grateful to me that I happened along when I did because he said the Cougar was facing him off and it was only a few feet away from him. It was just a year or so before a cougar killed a couple mountain bikers near there. Cougars here in Southern California do not have a healthy respect or fear of humans and can sometimes look at humans as potential food if they get hungry. Leopards probably have a similar situation in Africa with humans encroaching on their habitat. The vast majority are no problem but sometimes one will learn to hunt humans, usually a sick or old animal.
    8 answers · 3 days ago
  • Strange screaming sound in Northern Virginia?

    For the past two nights I ve been hearing this strange screaming sound from my window. It s definitely an animal not a person. I only hear it at night and can t seem to tell what it is. I recorded the sound but I m not sure how to post it on here. Any ideas of what it could be are appreciated.
    For the past two nights I ve been hearing this strange screaming sound from my window. It s definitely an animal not a person. I only hear it at night and can t seem to tell what it is. I recorded the sound but I m not sure how to post it on here. Any ideas of what it could be are appreciated.
    5 answers · 7 hours ago
  • If a canary was released from a ship in the middle of the Atlantic Ocean, could it fly to land?

    Best answer: Interesting question. A bald eagle made an Atlantic crossing in December 1987. When it was found in Ireland, it was so weak that it could be caught without a problem. In those days heavy westerly gales were raging across the ocean. Most likely the strong wind had blown the eagle out onto the ocean, too far to... show more
    Best answer: Interesting question. A bald eagle made an Atlantic crossing in December 1987. When it was found in Ireland, it was so weak that it could be caught without a problem.
    In those days heavy westerly gales were raging across the ocean. Most likely the strong wind had blown the eagle out onto the ocean, too far to return. And again it was the only power to make the happy end of that crossing possible. The exact starting point of the bird is unknown of course.

    A canary, released in the middle of the ocean in quiet weather? Maybe it wouldn't be completely impossible, but very unlikely.
    5 answers · 1 day ago
  • Most animals go through a reproduction cycle. What is the best reason for this?

    A. Males can mate with many females during breeding season B. Infants or offspring can be born in optimal conditions C. For the maturation and growth of an animal before it can reproduce again D. For the perpetration of their species.
    A. Males can mate with many females during breeding season B. Infants or offspring can be born in optimal conditions C. For the maturation and growth of an animal before it can reproduce again D. For the perpetration of their species.
    7 answers · 4 days ago
  • How is it that there is actually people in the world who aren't terrified of spiders?

    Best answer: I am not terrified of spiders. The reason I am not terrified of them is because there is no reason to be. Compared to humans spiders are small. Stamp on one with your size 9s and that is the end of spider. I am aware that some spiders can be venomous to humans but you will only be bitten if you threaten one. Hoards... show more
    Best answer: I am not terrified of spiders. The reason I am not terrified of them is because there is no reason to be. Compared to humans spiders are small. Stamp on one with your size 9s and that is the end of spider. I am aware that some spiders can be venomous to humans but you will only be bitten if you threaten one. Hoards of marauding spiders do not go looking for humans to attack. The fear of spiders is aptly named - arachnophobia. It is a phobia: An extreme or irrational fear or aversion. There are courses available to help you overcome it.
    6 answers · 3 days ago
  • Where do rattlesnakes go when it rains?

    8 answers · 5 days ago
  • What happens when animals in the wild get ticks?

    For example is lion cubs have ticks sucking their blood, attached to them, do they die eventually? They aren't like humans where they can remove them.
    For example is lion cubs have ticks sucking their blood, attached to them, do they die eventually? They aren't like humans where they can remove them.
    9 answers · 6 days ago
  • Why are ducks ******* retarded?

    23 answers · 1 week ago
  • Can a hyena bite a human's finger off?

    5 answers · 4 days ago
  • Are hippos and giraffes a type of horse?

    Zebras are obviously a horse, but I think hippos may be the water type and giraffes may be the plant type. Is there any evidence to support this theory?
    Zebras are obviously a horse, but I think hippos may be the water type and giraffes may be the plant type. Is there any evidence to support this theory?
    5 answers · 4 days ago
  • What is a mammal?

    7 answers · 6 days ago
  • Was earth’s gravity a lot less at one time?

    Best answer: Actually, you do need to look at the dinosaurs bone structure, and anatomy. https://www.theguardian.com/science/2009/feb/07/the-size-of-dinosaurs https://www.smithsonianmag.com/science-nature/how-to-build-a-giant-dinosaur-53490667/ http://www.sciencemag.org/news/2017/02/zigzagging-backbones-helped-turn-dinosaurs-giants show more
    Best answer: Actually, you do need to look at the dinosaurs bone structure, and anatomy.
    https://www.theguardian.com/science/2009/feb/07/the-size-of-dinosaurs
    https://www.smithsonianmag.com/science-nature/how-to-build-a-giant-dinosaur-53490667/
    http://www.sciencemag.org/news/2017/02/zigzagging-backbones-helped-turn-dinosaurs-giants
    10 answers · 1 week ago
  • Was there any Shark bigger then Megalodon?

    Best answer: We know very little about prehistoric extinct species. Large animals, especially aquatic, are almost impossible for us to find evidence of their existence. One reason is because it is rare for large animals to fossilize, the other reason is that aquatic species fossils are mostly under water! The few aquatic... show more
    Best answer: We know very little about prehistoric extinct species. Large animals, especially aquatic, are almost impossible for us to find evidence of their existence. One reason is because it is rare for large animals to fossilize, the other reason is that aquatic species fossils are mostly under water! The few aquatic species from the past that we know existed is thanks to moving tectonic plates that sometimes elevate thus exposing land that was once under shallow sea. There is ANOTHER problem with sharks specifically; only their teeth fossilize!

    Megalodon is the largest shark species we know of. Problem with sharks is that their skeleton is made out of cartilage-like ligaments, the only evidence we have of prehistoric sharks is their teeth. This bring up a major problem; the largest shark in the world now eats krill and have paper-sand like teeth which are almost impossible to fossilize.

    So, if there were giant krill eating sharks in the past, we will likely never know what they looked like or that they existed at all.
    Archeology is based on evidence, sadly sharks only evidence in the fossil records are their teeth.
    5 answers · 6 days ago
  • What type of insect is this?

    What type of insect is this?

    Best answer: It's a cockroach. Yuk!
    Best answer: It's a cockroach. Yuk!
    6 answers · 6 days ago
  • Animals are disappearing from my area,should I be concerned?

    Raccoons,opossums,armadillos,many types of birds, frogs toads, fire ants, bee's wasp, turtles deer and other animals, are disappearing from my area for no apparent reason. This does concern me as the habit tat in my area is intact.
    Raccoons,opossums,armadillos,many types of birds, frogs toads, fire ants, bee's wasp, turtles deer and other animals, are disappearing from my area for no apparent reason. This does concern me as the habit tat in my area is intact.
    5 answers · 5 days ago