One thing that fascinates me now that I'm doing quite a lot of running is the difference between male and female performance. The difference is reasonably consistent across all distances as this table of world recods by distance shows (taken from the IAAF).
Discipline
Perf
Athlete
Perf
Athlete
Difference% (F/M-1)
100 Metres
9.58
Usain Bolt
10.49
Florence Griffith-Joyner
9.50%
200 Metres
19.19
Usain Bolt
21.34
Florence Griffith-Joyner
11.20%
400 Metres
43.18
Michael Johnson
47.6
Marita Koch
10.24%
800 Metres
01:41.11
Wilson Kipketer
01:53.28
Jarmila Kratochvílová
12.04%
1000 Metres
02:11.96
Noah Ngeny
02:28.98
Svetlana Masterkova
12.90%
1500 Metres
03:26.00
Hicham El Guerrouj
03:50.46
Yunxia Qu
11.87%
One Mile
03:43.13
Hicham El Guerrouj
04:12.56
Svetlana Masterkova
13.19%
2000 Metres
04:44.79
Hicham El Guerrouj
05:25.36
Sonia O'Sullivan
14.25%
3000 Metres
07:20.67
Daniel Komen
08:06.11
Junxia Wang
10.31%
5000 Metres
12:37.35
Kenenisa Bekele
14:11.15
Tirunesh Dibaba
12.39%
10,000 Metres
26:17.53
Kenenisa Bekele
29:31.78
Junxia Wang
12.31%
10 Kilometres
27:01:00
Micah Kipkemboi Kogo
30:21:00
Paula Radcliffe
12.34%
15 Kilometres
41:29:00
Felix Limo
46:55:00
Kayoko Fukushi
13.10%
20,000 Metres
56:26.00
Haile Gebrselassie
01:05:26.60
Tegla Loroupe
15.97%
20 Kilometres
00:55:48
Haile Gebrselassie
01:02:57.00
Lornah Kiplagat
12.81%
One Hour*
21.29
Haile Gebrselassie
18.52
Dire Tune
14.95%
Half Marathon
00:58:33
Samuel Kamau Wanjiru
01:06:25
Lornah Kiplagat
13.44%
25 Kilometres
01:12:45
Paul Malakwen Kosgei
01:22:13
Mizuki Noguchi
13.01%
30 Kilometres
01:28:00
Takayuki Matsumiya
01:38:49
Mizuki Noguchi
12.29%
Marathon
02:03:59
Haile Gebrselassie
02:15:25
Paula Radcliffe
9.22%
100 Kilometres
06:13:33
Takahiro Sunada
06:33:11
Tomoe Abe
5.26%
*One hour is distance in km travelling in one hour hence the difference ratio is reversed
If you graph this you see that for the most part the female records are 12-14% slower (with some outliers) but that the trend distinctly drops at the ends. Particulalrly at the long end where the 100km time is far more equal. Also of interest is that while female record holders are from a variety of ethnic backgrounds (though no Indians) the male ones all come from an African background except for Takahiro Sunada in the 100km cetegory and Takatuki Matsumia in the 30km one. [Actually there are 2 other Japanese male record holders in the 25,000 meters and the 30,000 meters - I omitted these times in the comparison since it seems clear these are distances are weird in that these track records are significantly slower than the road equivalents for both sexes.]
Just to put these numbers in persepctive. I personally can run from 5km to marathon at times that are approximately 50% longer - (19 minutes 5-km, 39 mins 10km, 1h26 for half marathon and 3h15 for the full) - than the male world record holders. I also generally finish in the top 10-20% of finishers. Slower runners often take more than 50% longer to finish than I do so.
I suspect that outside of professional athletics the m-f difference is on average larger. For example when I look at the times for the first female finisher compared to the winner (always male) in the smaller races I take part in the difference seems to be larger than 10-15%. Indeed I quite often beat - or come in close behind - the leading woman in these smaller races).
One reason why I'm going on about this is that people generally accept that in sports female competitors/teams at a certain level will be beaten by male ones at the same level. Indeed think of all the controversy about Caster Semenya just now. In fact I'm not in fact aware of any major sport which relies on human muscles where women compete on equal terms ot men. On the other hand there is huge controversy over potential intellectual differences. William Briggs has a series of posts discussing "Fads and Fallacies in the Social Sciences" by Steven Goldberg where the statistics about that possible difference (mean IQs same, males show higher varience hence more males as outliers at the top and bottom of the range) and how people refuse to accept evidence that points to the difference or the consequences of such a difference.
The other reason I'm thinking about this is because of fictional books where the heroine is some kind of physical superwoman. Unless she's genetically engineered like Friday or Honor Harrington this is going to be hard to swallow unless there are clear compensatory reasons such as coming from a different ethnic group where both sexes are generally bigger and stronger (think N Europe vs SE Asia for example).