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Currently, we have around 7.5 billion people on earth, and 150,000 deaths per day.

But a while ago, there were fewer people. At some point in the past, there must have been a day when nobody died. Approximately when was that?

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  • Sure, a day before there were humans. Let's say 2 million years ago? Alternatively we can go roughly 3.5 to 4 billion years into the past - the likelihood of anyone but your odd time traveller dying is pretty low.
    – Anaryl
    Mar 1 '17 at 5:20
  • @Anaryl that's not most recents.
    – Tim
    Mar 1 '17 at 7:52
  • Sure it could be. The conditional is the most recent - i.e the last time it occurred. If there hasn't been a day without a hominid death in 2 million years, then by definition the most recent day without a hominid death was 2 million and one years ago.
    – Anaryl
    Mar 1 '17 at 8:05
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    One back-of-a-napkin approach would be: every day 0.002% of humanity die (disregarding new births). So wildly assuming unlikely occurrences such as a constant daily death rate - or at least one that averages out over time - guess would be something like "at what human population is 0.002% less than 1?" It's late, but unless I butterfingered on my calculator that would be at less than 50,000 people. Someone more wide awake than me can correct any shifting decimal point errors.
    – Marakai
    Mar 1 '17 at 10:18
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    Vote to reopen: This question is not opinion based. It's just an statistical question that can be estimated with available data. FYI, when population was 100.000 and assuming a crude death rate like those of Mali or Angola in 1960, a day with no deaths could be expected once in 100 years.
    – Pere
    Mar 1 '17 at 11:55
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You would probably have to go way back into pre-history.

If we assume average life expectancy of early man to be 20 years, and allow one death per day, the population could be as low as 7,300. Mind you, this is an average and it would only take one person to be early/late to have two deaths one day and no deaths on the day before/after. Let's say we need 73,000 people to ensure at least one death per day.

Scholars believe that around the time of the speciation of Homo Sapiens (130,000 years ago), there was already an effective population of about 10,000 to 30,000 (which gives a "census" or actual population size of between 100,000 to 300,000 - which is already at the limit).

So - there has likely not been a day for 130,000 years where a human has not died (and it could be argued that there has never been such a day, since there were no "humans" before speciation).

Note: there is postulation of a bottleneck about 70,000 years ago where the population of Homo Sapiens dropped to 10,000 or less, but this is currently disputed - mainly because of the difference between "effective" and "census" populations. "Effective" population includes all members who successfully reproduced: however not all population members do reproduce.

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Never, because there was always a population of human ancestors. You can try to pinpoint an exact moment to call them human (i wouldn't bother) but whenever you choose, there will always be enough that someone died.

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  • What about the period from 4.5 - 13 and 1/2 billion years ago?
    – Anaryl
    Mar 1 '17 at 5:19
  • Were there any humans 4.5 billion years ago? Or 0.5 billion years ago? When I was bringing up the definition of human I took it for granted we meant some kind of primate. Maybe this shows the question is on the wrong stack.
    – Ne Mo
    Mar 1 '17 at 7:33
  • Yes its more likely its a statistics/demographics based question - since history is partly the study of recorded sources and I'm fairly certain there are no records for this, then we're being asked to speculate so its either a statistics/demographics question or a biology question.
    – Anaryl
    Mar 1 '17 at 8:07
  • @Anaryl Historical demography is in the scope of history, and statistics is just the tool to compute the answer, not the topic of the question.
    – Pere
    Mar 1 '17 at 15:30
  • Any answer would be inherently speculative, would make reference to no sources and would rely purely on inference of dubious statistics. We're not referring to any actual demographies, just doing back of the envelope speculation. The scope for actual history is very limited indeed.
    – Anaryl
    Mar 1 '17 at 18:20

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