The time gap within a generation

When looking at our youngest grandson, it ocurred to me that the little guy is the "product" of not only his parents. Many generations have contributed to his DNA, to his character, to his brainpower, to the way he looks etc. If you go back far enough, say seven generations, usually there are 2⁷ persons equalling 128 men and women who have unknowingly helped our grandson to become what he is and what he will be.
If I try to envisage what a generation looks like, I see a small number of people of about the same age, e.g. my four grandparents. They have all been born within 12 years of eachother. 
It seems obvious that the further you go back, that time span will increase. But I had no idea what that figure would be. 
So I consulted my genealogical data and selected all persons being part of that particular seventh generation. Of those I eliminated (sorry ancestors) all those of which the year of birth and death are unknown to me. Also I still have to look up 32 persons being the ancestors of my daughter-in-law's father. So they are not in as well. Taking all this into account, 57 ancestors remain. They are shown below.

NAME	YEAR
	BORN	DIED
Fredericus Muwis	1760	1834
Jacoba Betger		1833
Jan Hoksteen	1774	1812
Maria van Deudekom	1774	1842
Pieter van Oosten	1775	1852
Alida van Oosten	1779	1840
Leendert Barmond	1761	1816
Maria Plokhaar	1771
Korstiaan Kok		1844
Huigje Dirks Russel	1774	1821
Jan de Langen	1792
Maria Hendrika Carstens	1795	1867
Jacob Doelman	1804	1894
Maria van Berkel	1804	1848
Adam Barendregt	1794	1864
Jakoba Kleijwegt	1805
Lodewijk Orie	1807	1867
Dirkje Langeveld	1808	1853
Willemina Sprinkhuizen	1849	1905
Syger Reitses Visser	1789
Reintje Goitzes Zijlstra	1783
Francis van Asten	1802
Johanna van de Langeweg	1805
Nicolaas van Leeuwen	1811
Mietje Kans	1814
Willem Voortman	1802	1879
Adriana Kampert	1806
Rutgert Berends Venema	1811	1885
Jantie Hommes Klein	1802	1875
Geert Heikes Knip	1823
Jantje Hindriks Lemain	1820	1884
Doede Heines Klopstra	1788	1863
Hendrikje Mattheus van Halen	1797	1861
Jan Hendriks Schokker	1803	1876
Grietje Gerrits Duiker	1811	1859
Johannes Walles Veldhuis	1809
Sibbeltje Pieters Boomsma	1813
Pieter Hendrik Verburg	1807
Anna Sanderina Meulenberg	1809
Thomas Maat	1798	1862
Pieternella Verburg	1807	1880
Marcus Marcusse	1810	1880
Maria de Waal	1819	1878
Jan Breas	1792
Leintje Tazelaar	1804	1872
Gerard Adriaan Israel	1799
Maria Belleman	1799	1833
Cornelis Boot	1811
Lena van der Maas	1810
Jacob van Leeuwen	1773	1833
Pieternella van der Maas	1785	1855
Hendrik ter Burg	1806
Antje Trap	1802	1839
Jan van der Kemp	1801
Elisabeth Jansen	1801
Jan Weij	1814
Guurtje Veter	1821

As you can see, the time frame of all births is between 1760-1849 (89 years). Deaths took place between 1812-1905 (93 years). So these ancestors lived anytime between 1760 and 1905 which to me is an amazing 145 years! All in the same generation. The question of course is where all these big numbers come from.
I can think of two reasons. 
Certainly during the 18th, 19th and also during the first part of the 20th century, married couples in this part of Europe had many children. 10 or more was not uncommon. If for whatever reason the mother died (e.g. in childbirth), the father generally remarried fairly soon. He had to for practical reasons. Who else could run the household and take care of all the young ones? So in many cases there was a considerable age difference between the partners.
Another factor that will increase the time gap within a generation, may be caused by a marriage between an oldest child in one family and the youngest child in another family.
Both occurrences will certainly amplify each other. And if such events took place in subsequent generations, the time gap within a single generation will increase even further.


It is a funny idea that if all these contemporaries would have lived in the same area, they might have known each other without realizing they would be "joined" a few centuries later. The proof of the pudding is in the eating so I had a look at where those 57 ancestors were born. But even in a small country like The Netherlands they often lived more than 100 miles apart. And since travelling in those days was quite an enterprise, there is little chance they actually ever met, spouses excluded...

Distribution of ancestor places of birth in The Netherlands
and Belgium. The maximum distance between any two places
is a little over 200 miles.

Any (deviating) views on the above will be appreciated. And if you have calculated time gaps as well, I'll be interested to know.