Too Many Firstborns in Numbers 3?

Let's Do the Math

The Problem

In Numbers 3, in the second year of the exodus, Moses takes a census of Israel. In all he counts 22,273 firstborn men (of age at least one month).

Quite a few folk have questioned the accuracy of Moses’s figure. The reason why is summed up in the argument below.

• In Numbers 1, the Israelites are said to have 603,550 warriors at their disposal (Num. 1.46).

• To be a warrior, you had to be at least twenty and not too old to fight.

• If 80% of the Israelites’ male population met the above criterion (a reasonable enough assumption), it would mean there were about 750,000 Israelite males alive at the time of the exodus.

• But, if only 22,000 of those 750,000 men were firstborns, then only one in every 34 men would have been a firstborn, which seems too low. It means the average man would need to have fathered 70 children.

So what’s gone wrong here?

The answer, in a word, is nothing. If the exodus narrative is true, then the Israelites would almost certainly have emerged from Egypt with a very low number of firstborn children. Here’s why.

Three Considerations

Consideration §1: The exodus narrative is predicated on extraordinary population growth.

In the text of Exodus 1, against the backdrop of God’s promise to make Abraham fruitful, the Israelites multiply far beyond the normal rate. They fill the land of Egypt (which is said to ‘teem’ with them), and possibly even outnumber the Egyptians (Exod. 1.9). Pharaoh thus becomes fearful of the Israelites. And, when the midwives tell him why they haven’t slain the Israelites’ newborn boys, their answer is predicated on how rapidly the Israelite women give birth (and/or conceive?) (Exod. 1.19), which Pharaoh seems to accept as true at some level. (At any rate, Pharaoh doesn’t have the midwives slain for their disobedience.)

Given what we’re told in Exodus 1, then, we’d expect the average Israelite man to have fathered abnormally large numbers of children, which would have resulted in an abnormally low ratio of firstborns-to-non-firstborns.

True, it’s hard to imagine how the average Israelite woman could have undergone seventy pregnancies in the space of, say, thirty years, but then that’s almost certainly not what happened.

If the ages of Moses and his father are anything to go by (120 and 137 respectively), then the Israelites enjoyed unusually long lives, which means the Israelites could have borne children for almost twice as long as the average woman does today.

Furthermore, many of the Israelites could have borne twins or triplets (or even larger batches of children). In the 18th century, a Russian woman named Valentina Vassilyeva is said to have borne 69 children, included among whom were sixteen pairs of twins, seven sets of triplets, and four sets of quadruplets. And, curiously, in his comments on Exodus 1.7, Rashi quotes a Jewish tradition which says many women gave birth to sextuplets prior to the exodus. (The tradition is grounded in unusual exegesis, but it may nevertheless preserve a reliable historical memory of Israel’s past.)

Of course, those who question Numbers 3’s firstborn count might also be inclined to question Exodus 1–15’s claims about the Israelites’ population growth and lifespans, but, when we assess the plausibility of the Biblical narrative, we need to assess it as a whole. We can’t grant some bits of it, disregard other bits of it, and then claim the end result is incoherent. (Most texts are incoherent if you remove large portions of them.)

In sum, then, God could, theoretically, have caused each woman in Israel to bear 70 children and hence brought about the firstborns-to-non-firstborn ratio we have in Numbers 3, which suffices to undercut the objection at hand. (To put the point another way, when God makes a nation extraordinarily fruitful, it’s bound to result in an extraordinarily low ratio of firstborns-to-non-firstborns.)

As our next two considerations will demonstrate, however, things are more complicated than that, since other aspects of the Biblical narrative need to be taken into account.

Consideration §2: Prior to the exodus, the male-to-female ratio in Israel would have been abnormally low.

In the events of Exodus 1 (set 80 years before the exodus), Pharaoh orders his people to drown the Israelites’ newborn boys.

How ‘successful’ Pharaoh’s policy was (and how long it was enforced for) isn’t stated. But suppose, for the sake of illustration, his actions meant there were only a third of the expected number of Israelite men alive at the time of the exodus. Each Israelite could then have married an average of three Israelite women, which would reduce the average number of children each woman needs to have borne to nearer 25. (If a man married three women and had 25 children with each of them, only one of his 75 children would have counted as his firstborn son.)

Consideration §3: Many of the Israelites’ firstborn sons could have been slain on the night of the Passover.

The Bible doesn’t paint a very rosy picture of the Israelites’ faithfulness in Egypt. Ezekiel tells us they were thoroughly entangled in Egypt’s idolatry (Ezek. 20.8–9), and not long after the exodus they happily erected and worshipped a golden calf (Exod. 32).

Suppose, then, two-thirds of the Israelites failed to apply the blood of a lamb to their doorposts. (The sacrifice of a lamb would have made them unpopular with the Egyptians, so many of them may not have bothered for that reason alone: Exod. 8.26.) In that case, two-thirds of the Israelites’ firstborns would have died on the night of the Passover, so the average Israelite woman would only need to have borne eight children (or, more precisely, eight children who survived infancy).

Assessment

While at first blush the ratio of firstborns-to-non-firstborns in Numbers 3 looks odd, it turns out (on closer inspection) to be exactly the kind of ratio we could reasonably expect to see if the events of Exodus 1–15 really took place. What would be odd to see (given Exodus 1–15) is a more standard ratio of firstborns-to-non-firstborns. As with all things Biblical, context is key. When God does extraordinary things, extraordinary statistics can arise.