# How many generations are we removed from various common ancestors? **URL:** \ **Category:** Factual Questions\ **Created:** [February 11, 2014, 10:34pm UTC](https://boards.straightdope.com/t/how-many-generations-are-we-removed-from-various-common-ancestors/681094 "2014-02-11T22:34:16Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![sweeteviljesus](https://avatars.discourse-cdn.com/v4/letter/s/898d66/32.png) [@sweeteviljesus](https://boards.straightdope.com/u/sweeteviljesus)\ **Post date:** [February 11, 2014, 10:34pm UTC](https://boards.straightdope.com/t/how-many-generations-are-we-removed-from-various-common-ancestors/681094/1 "2014-02-11T22:34:16Z")
For example, how many generations removed are we from the last common ancestor of humans? From last common ancestor of us and chimpanzees? From the last common ancestor of all mammals? If you know, please keep going as far back as you like. Someone once told me that all humans are at most 50th cousins from each other. Is that accurate? Thanks, Rob ---
**Author:** ![BlakeTyner](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@BlakeTyner](https://boards.straightdope.com/u/BlakeTyner)\ **Post date:** [February 11, 2014, 11:02pm UTC](https://boards.straightdope.com/t/how-many-generations-are-we-removed-from-various-common-ancestors/681094/2 "2014-02-11T23:02:06Z")
Just doing some back-of-the-envelope calculations… The Wiki article on the most recent human ancestor gives the number as 2,000-4,000 years ago. I used an average lifespan of 35 years (arbitrary, but I figure high mortality at that point would skew the average to the low end.) So that gives you between 57 and 114 generations to that point. Going back further, from Wiki (quoting Richard Dawkins): Another way of looking at this is to say that our (approximately) 250,000-greats-grandparent was a creature from which all humans, chimpanzees and bonobos are directly descended. Further on in Dawkins’ imaginary journey (imaginary, in that the journey is going backwards in time), we meet the concestor we share with the gorilla, our next nearest relative, then the orangutan, and so on, until we finally meet the concestor of all living organisms, known as the last universal ancestor. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [February 11, 2014, 11:12pm UTC](https://boards.straightdope.com/t/how-many-generations-are-we-removed-from-various-common-ancestors/681094/3 "2014-02-11T23:12:22Z")
By “last common ancestor of humans”, do you mean the common ancestor of all humans alive _now_, or the common ancestor of all humans _ever_? The former is, as **BlakeTyner** noted, fairly recent, and so that person’s contemporaries, and parents, and grandparents, and great-great-great-great-great grandparents would have been humans, too. ---
**Author:** ![OldGuy](https://avatars.discourse-cdn.com/v4/letter/o/3bc359/32.png) [@OldGuy](https://boards.straightdope.com/u/OldGuy)\ **Post date:** [February 11, 2014, 11:14pm UTC](https://boards.straightdope.com/t/how-many-generations-are-we-removed-from-various-common-ancestors/681094/4 "2014-02-11T23:14:27Z")
> [@BlakeTyner](#): > > Just doing some back-of-the-envelope calculations… > > The Wiki article on the most recent human ancestor gives the number as 2,000-4,000 years ago. > > I used an average lifespan of 35 years (arbitrary, but I figure high mortality at that point would skew the average to the low end.) > > So that gives you between 57 and 114 generations to that point. You don’t want to use the average lifespan, you want to use the average age of becoming a parent. Note many people become a parent more than once so you want the average parent across all births not the average age of first becoming a parent. This is certainly lower than 35. And for most of human prehistory was probably less than 20. But using 20, the answer is 100 to 200 generations. ---
**Author:** ![BlakeTyner](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@BlakeTyner](https://boards.straightdope.com/u/BlakeTyner)\ **Post date:** [February 11, 2014, 11:25pm UTC](https://boards.straightdope.com/t/how-many-generations-are-we-removed-from-various-common-ancestors/681094/5 "2014-02-11T23:25:58Z")
> [@OldGuy](#): > > You don’t want to use the average lifespan, you want to use the average age of becoming a parent. Note many people become a parent more than once so you want the average parent across all births not the average age of first becoming a parent. This is certainly lower than 35. And for most of human prehistory was probably less than 20. But using 20, the answer is 100 to 200 generations. Good call; I’d just happened to have been curious about that question the other day, and remembered a couple of the data points from reading up on it. My education is in the humanities, which, while it sounds like it’d make me an expert at answering this question, actually means some quick division is about all I’m good for! ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [February 11, 2014, 11:33pm UTC](https://boards.straightdope.com/t/how-many-generations-are-we-removed-from-various-common-ancestors/681094/6 "2014-02-11T23:33:06Z")
> [@BlakeTyner](#): > > The Wiki article on the most recent human ancestor gives the number as 2,000-4,000 years ago. Er, that is at least a couple of orders of magnitude out, dude. Even the Young Earth Creationists have humans around for 6,000+ years. ---
**Author:** ![BlakeTyner](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@BlakeTyner](https://boards.straightdope.com/u/BlakeTyner)\ **Post date:** [February 11, 2014, 11:36pm UTC](https://boards.straightdope.com/t/how-many-generations-are-we-removed-from-various-common-ancestors/681094/7 "2014-02-11T23:36:21Z")
> [@njtt](#): > > Er, that is at least a couple of orders of magnitude out, dude. Even the Young Earth Creationists have humans around for 6,000+ years. The MRCA isn’t a single individual…it changes with populations. Like the poster above said, that’s for all humans alive NOW; if you’re looking for the MRCA for all humans EVER, then it goes back much further. Going by the estimate of modern humans emerging around 250,000 years ago, that’d be 12,500 generations (assuming 20 as a “generation.”) To go back to the point where you get Homo Sapiens, chimps, and bonabos, per Dawkins, that’s 250,000 generations. ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [February 11, 2014, 11:41pm UTC](https://boards.straightdope.com/t/how-many-generations-are-we-removed-from-various-common-ancestors/681094/8 "2014-02-11T23:41:35Z")
> [@BlakeTyner](#): > > The MRCA isn’t a single individual…it changes with populations. Like the poster above said, that’s for all humans alive NOW; if you’re looking for the MRCA for all humans EVER, then it goes back much further. From the context of the rest of his question, where the OP asks also about the last common ancestor of chimps and humans, and the last common ancestor of all mammals, I think it is clear that he meant the last ancestor who was not _homo sapiens_, so yes, all humans ever. ---
**Author:** ![BlakeTyner](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@BlakeTyner](https://boards.straightdope.com/u/BlakeTyner)\ **Post date:** [February 11, 2014, 11:53pm UTC](https://boards.straightdope.com/t/how-many-generations-are-we-removed-from-various-common-ancestors/681094/9 "2014-02-11T23:53:23Z")
> [@njtt](#): > > From the context of the rest of his question, where the OP asks also about the last common ancestor of chimps and humans, and the last common ancestor of all mammals, I think it is clear that he meant the last ancestor who was not _homo sapiens_, so yes, all humans ever. Which is why I continued typing in my original response, and gave the Dawkins answer of 250,000 generations to get to the point where we see homo sapiens sapiens, chimps, and bonabos. ---
**Author:** ![Melchior](https://avatars.discourse-cdn.com/v4/letter/m/e5b9ba/32.png) [@Melchior](https://boards.straightdope.com/u/Melchior)\ **Post date:** [February 12, 2014, 1:41am UTC](https://boards.straightdope.com/t/how-many-generations-are-we-removed-from-various-common-ancestors/681094/10 "2014-02-12T01:41:14Z")
> [@BlakeTyner](#): > > Which is why I continued typing in my original response, and gave the Dawkins answer of 250,000 generations to get to the point where we see homo sapiens sapiens, chimps, and bonabos. Just look up the time of the hominid-chimp split (5 millions years?) and divide by 20 (approximate age of reproduction). Then you have to deal with anomalies such as the Pharaoh Ramses II, who fathered about 100 children (or so). ---
**Author:** ![Dervorin](https://avatars.discourse-cdn.com/v4/letter/d/eb8c5e/32.png) [@Dervorin](https://boards.straightdope.com/u/Dervorin)\ **Post date:** [February 12, 2014, 9:07am UTC](https://boards.straightdope.com/t/how-many-generations-are-we-removed-from-various-common-ancestors/681094/11 "2014-02-12T09:07:51Z")
This is an excellent book by Richard Dawkins that addresses this question, all the way back to the dawn of life - he estimates the number of generations between various “rendezvous” points such as the common ancestor of all humans, the common ancestor between humans and chimpanzees. Excellent, if somewhat dense, book. > **[The Ancestor's Tale](https://en.wikipedia.org/wiki/The_Ancestor's_Tale)** > > The Ancestor's Tale: A Pilgrimage to the Dawn of Life is a science book by Richard Dawkins and Yan Wong that delves into the topic of evolution. The book adopts a unique approach, retracing the path of humans in reverse chronological order through evolutionary history. Along the way, it introduces readers to various species, referred to as humanity's cousins, as they converge on shared common ancestors. Drawing on scientific principles and research, "The Ancestor's Tale" offers an accessible a... ---
**Author:** ![bienville](https://avatars.discourse-cdn.com/v4/letter/b/4bbf92/32.png) [@bienville](https://boards.straightdope.com/u/bienville)\ **Post date:** [February 12, 2014, 11:51am UTC](https://boards.straightdope.com/t/how-many-generations-are-we-removed-from-various-common-ancestors/681094/12 "2014-02-12T11:51:52Z")
I recently just read a little bit about [Mitochondrial Eve](http://en.wikipedia.org/wiki/Mitochondrial_Eve), and here’s the part that confuses me: [ul] [li]Why isn’t Mitochondrial Eve’s _mother_ actually Mitochondrial Eve (and what about _her_ mother, and what about _her_ mother)?[/li][/ul] ---
**Author:** ![BlakeTyner](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@BlakeTyner](https://boards.straightdope.com/u/BlakeTyner)\ **Post date:** [February 12, 2014, 12:54pm UTC](https://boards.straightdope.com/t/how-many-generations-are-we-removed-from-various-common-ancestors/681094/13 "2014-02-12T12:54:08Z")
> [@bienville](#): > > I recently just read a little bit about [Mitochondrial Eve](http://en.wikipedia.org/wiki/Mitochondrial_Eve), and here’s the part that confuses me: > [ul] > [li]Why isn’t Mitochondrial Eve’s _mother_ actually Mitochondrial Eve (and what about _her_ mother, and what about _her_ mother)?[/li][/ul] I _think_ based on my read of this sentence in the wiki article: “Mitochondrial Eve is the most recent common matrilineal ancestor for all modern humans. Whenever one of the two most ancient branch lines dies out, the MRCA will move to a more recent female ancestor, _always the most recent mother to have more than one daughter_ with living maternal line descendants alive today.” [Emphasis mine] The implication is that Mitochondrial Eve’s mother only had one daughter, who then produced more than one daughter. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [February 12, 2014, 1:10pm UTC](https://boards.straightdope.com/t/how-many-generations-are-we-removed-from-various-common-ancestors/681094/14 "2014-02-12T13:10:01Z")
In my genealogical research, going back a thousand years, the average generation span comes out consistently around 31 years. Note that that number varies in the last couple centuries as people started having fewer children, ending their childbearing years earlier. Also the date of first child varies in different eras. Sometimes people didn’t start families until late due to the need for the man to get his own farm or other business going. But over many millennia, the 31 year gap seems pretty good. ---
**Author:** ![bienville](https://avatars.discourse-cdn.com/v4/letter/b/4bbf92/32.png) [@bienville](https://boards.straightdope.com/u/bienville)\ **Post date:** [February 12, 2014, 1:29pm UTC](https://boards.straightdope.com/t/how-many-generations-are-we-removed-from-various-common-ancestors/681094/15 "2014-02-12T13:29:58Z")
> [@BlakeTyner](#): > > I _think_ based on my read of this sentence in the wiki article: Thanks, **BlakeTyner**! When I was reading a few weeks ago I had first read a very sciencey article that one of the news sites had posted. Then I went to the Wiki page to try to understand better- but, by then I had already read too much sciencey stuff and my eyes were glazing over even at the start of the Wiki article so my reading comprehension must have been lacking. ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [February 12, 2014, 1:58pm UTC](https://boards.straightdope.com/t/how-many-generations-are-we-removed-from-various-common-ancestors/681094/16 "2014-02-12T13:58:35Z")
> [@BlakeTyner](#): > > The implication is that Mitochondrial Eve’s mother only had one daughter, who then produced more than one daughter. Nitpick: Mitochondrial Eve’s mother had only one daughter _with living uterine descendants._ > [@ftg](#): > > In my genealogical research, going back a thousand years, the average generation span comes out consistently around 31 years. Fathers are, on average, 7 years or so older than mothers. Since many long cited lineages are mostly male, the apparent length of generations increases. We’ve had many many threads on this and related topics. [In this post I gave the agnatic and uterine ancestries of Prince Albert (Victoria’s consort)](http://boards.straightdope.com/sdmb/showpost.php?p=16335666&postcount=10) and noted > [@](#): > > His purely agnatic 26-great grandfather was born in the 9th century. His purely uterine 26-great grandmother was born in the 12th century. The average agnatic generation was 33 years; uterine generation 24 years. ---
**Author:** ![BlakeTyner](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@BlakeTyner](https://boards.straightdope.com/u/BlakeTyner)\ **Post date:** [February 12, 2014, 2:07pm UTC](https://boards.straightdope.com/t/how-many-generations-are-we-removed-from-various-common-ancestors/681094/17 "2014-02-12T14:07:16Z")
> [@bienville](#): > > Thanks, **BlakeTyner**! When I was reading a few weeks ago I had first read a very sciencey article that one of the news sites had posted. Then I went to the Wiki page to try to understand better- but, by then I had already read too much sciencey stuff and my eyes were glazing over even at the start of the Wiki article so my reading comprehension must have been lacking. Completely understand! I find the subject fascinating, but there are some complexities (particularly when you start getting into any kind of math past arithmetic, lol) that I get confused about. It looks like **septimus** has a better grasp of this stuff than I do, fortunately! ---
**Author:** ![John\_DiFool](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_difool/32/19543_2.png) [@John\_DiFool](https://boards.straightdope.com/u/John_DiFool)\ **Post date:** [February 12, 2014, 2:23pm UTC](https://boards.straightdope.com/t/how-many-generations-are-we-removed-from-various-common-ancestors/681094/18 "2014-02-12T14:23:10Z")
2-4,000 years seems too recent to account for isolated populations (such as Australian indigents, if that is the right word). ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [February 12, 2014, 3:04pm UTC](https://boards.straightdope.com/t/how-many-generations-are-we-removed-from-various-common-ancestors/681094/19 "2014-02-12T15:04:56Z")
> [@bienville](#): > > I recently just read a little bit about [Mitochondrial Eve](http://en.wikipedia.org/wiki/Mitochondrial_Eve), and here’s the part that confuses me: > [ul] > [li]Why isn’t Mitochondrial Eve’s _mother_ actually Mitochondrial Eve (and what about _her_ mother, and what about _her_ mother)?[/li][/ul] Because mtDNA Eve is the most recent matrilineal ancestor. Surely the daughter is more recent than the mother, no? 😉 As for the OP, pick whichever lifespan you think is most accurate and then extrapolate back. Modern Human and Neanderthal split is about 500k years ago. Human and Chimp lines split about 6M years ago. But keep in mind that the further back in time you go, generations almost certainly become less human-like and more chimp-like, assuming our common ancestor was more chimp like in reproduction than human-like. ---
**Author:** ![iiandyiiii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/iiandyiiii/32/7924_2.png) [@iiandyiiii](https://boards.straightdope.com/u/iiandyiiii)\ **Post date:** [February 12, 2014, 3:16pm UTC](https://boards.straightdope.com/t/how-many-generations-are-we-removed-from-various-common-ancestors/681094/20 "2014-02-12T15:16:20Z")
> [@John\_DiFool](#): > > 2-4,000 years seems too recent to account for isolated populations (such as Australian indigents, if that is the right word). Even ‘isolated’ populations were probably not truly isolated. They may have, very occasionally (like once every few hundred years), had enough contact with surrounding groups to interbreed. Just imagine a lost baby or adult in the forest, adopted by the ‘isolated’ tribe (or vice versa), happening every few hundred years thousands of years ago. [Next page](https://boards.straightdope.com/t/how-many-generations-are-we-removed-from-various-common-ancestors/681094.md?page=2)