1
00:00:01,920 --> 00:00:06,560
Speaker 1: Welcome to brain Stuff production of I Heart Radio, Hey

2
00:00:06,640 --> 00:00:10,399
Speaker 1: brain Stuff Lauren Bogelbaum. Here, the world is made up

3
00:00:10,400 --> 00:00:14,680
Speaker 1: of about right handed people and ten percent left handed people.

4
00:00:15,320 --> 00:00:18,480
Speaker 1: Folks who are truly ambidexterous those who use their right

5
00:00:18,520 --> 00:00:21,600
Speaker 1: and left hand equally well make up a negligible sliver

6
00:00:21,720 --> 00:00:27,240
Speaker 1: of the population. But is ambidexterity inherited or learned? And

7
00:00:27,560 --> 00:00:31,200
Speaker 1: if learned, can it be learned as an adult? We

8
00:00:31,520 --> 00:00:34,920
Speaker 1: spoke by email with Dr Sebastian Aucklenberg, a professor of

9
00:00:34,960 --> 00:00:39,159
Speaker 1: psychology at Rural University in Bochum, Germany. He said a

10
00:00:39,200 --> 00:00:42,360
Speaker 1: little bit of both. Handedness is determined by about twenty

11
00:00:42,600 --> 00:00:47,840
Speaker 1: percent genetic factors and non genetic factors like environmental influences.

12
00:00:48,200 --> 00:00:50,839
Speaker 1: It clearly runs in families, so it is somewhat inherited,

13
00:00:51,080 --> 00:00:54,600
Speaker 1: but learning might also affect it. I think ambidexterity for

14
00:00:54,680 --> 00:00:58,160
Speaker 1: a specific task like hitting a tennis ball with a racket,

15
00:00:58,320 --> 00:01:04,560
Speaker 1: is possible, but full ambodexterity for all tasks is unlikely. Handedness,

16
00:01:04,720 --> 00:01:07,360
Speaker 1: being the skill and comfort of person feels using one

17
00:01:07,440 --> 00:01:10,479
Speaker 1: hand or the other, is considered a complex genetic trait,

18
00:01:11,000 --> 00:01:14,640
Speaker 1: and since genes are involved, hand preference develops before a

19
00:01:14,640 --> 00:01:18,759
Speaker 1: person is even born, But like other complex traits, handedness,

20
00:01:18,840 --> 00:01:23,880
Speaker 1: including ambedoxterity, doesn't have a simple pattern of inheritance. Yes,

21
00:01:23,920 --> 00:01:26,319
Speaker 1: there is a greater chance that children of left handed

22
00:01:26,360 --> 00:01:29,440
Speaker 1: parents will also be left handed than children of rights,

23
00:01:29,880 --> 00:01:32,280
Speaker 1: but remember the chance of being a lefty is just

24
00:01:32,319 --> 00:01:35,559
Speaker 1: ten percent overall, so most children of lefties are still

25
00:01:35,640 --> 00:01:39,880
Speaker 1: right handed, and identical twins are more likely than non

26
00:01:39,920 --> 00:01:42,959
Speaker 1: identical twins to both be either right or left handed,

27
00:01:43,200 --> 00:01:46,960
Speaker 1: but many of both types do have opposite hand preferences.

28
00:01:47,000 --> 00:01:50,080
Speaker 1: And that's before we even talk about whether a child's

29
00:01:50,120 --> 00:01:53,400
Speaker 1: handedness is allowed to develop naturally or whether parents and

30
00:01:53,440 --> 00:01:58,840
Speaker 1: teachers interfere. Hand dominance typically develops around age three and

31
00:01:59,000 --> 00:02:01,600
Speaker 1: is fully developed by age four to five, but it

32
00:02:01,640 --> 00:02:04,680
Speaker 1: can be influenced by insisting a child uses their other

33
00:02:04,720 --> 00:02:09,320
Speaker 1: hand or by happenstance. For example, when he was four

34
00:02:09,400 --> 00:02:13,320
Speaker 1: years old, former Major League baseball pitcher Billy Wagner broke

35
00:02:13,400 --> 00:02:15,840
Speaker 1: his right elbow and spent the summer in a cast.

36
00:02:16,639 --> 00:02:20,440
Speaker 1: In his memoir, Wagner vividly recalls being a natural righty

37
00:02:20,480 --> 00:02:23,600
Speaker 1: at the time and already mad for baseball, but for

38
00:02:23,600 --> 00:02:27,000
Speaker 1: the next six weeks he threw only left handed. When

39
00:02:27,000 --> 00:02:29,120
Speaker 1: the cast came off, he was in for a surprise

40
00:02:29,480 --> 00:02:32,480
Speaker 1: when he tried throwing with his right The ball went nowhere.

41
00:02:33,040 --> 00:02:36,360
Speaker 1: Had lost not just strength but coordination for throwing with

42
00:02:36,440 --> 00:02:40,600
Speaker 1: his right arm and gained it in his left. Wagner wrote,

43
00:02:40,919 --> 00:02:43,480
Speaker 1: I was a natural righty then and still am. I

44
00:02:43,560 --> 00:02:46,840
Speaker 1: do everything right handed, eat hold tools, right to start

45
00:02:46,840 --> 00:02:53,480
Speaker 1: the lawnmower, everything except pitch. Wagner wouldn't be considered ambidextrous,

46
00:02:53,600 --> 00:02:56,960
Speaker 1: though he certainly managed to have an incredibly successful career

47
00:02:57,120 --> 00:03:00,520
Speaker 1: working with his non dominant hand. Base all is full

48
00:03:00,560 --> 00:03:03,520
Speaker 1: of players who switch hit, meaning they hit equally well

49
00:03:03,600 --> 00:03:06,280
Speaker 1: from either the left or right side and are comfortable

50
00:03:06,360 --> 00:03:09,840
Speaker 1: facing left or right handed pitchers. Some like Hall of

51
00:03:09,880 --> 00:03:14,000
Speaker 1: famers Eddie Murray, Mickey Mantle, and Chipper Jones, were very successful,

52
00:03:14,639 --> 00:03:18,720
Speaker 1: but they, like Wagner, weren't truly ambidexterous, which is something

53
00:03:18,800 --> 00:03:25,160
Speaker 1: that's very difficult to do. But why. Aucklenburg said, handedness

54
00:03:25,240 --> 00:03:28,280
Speaker 1: is something that is generated in the brain, not the hands.

55
00:03:28,760 --> 00:03:31,360
Speaker 1: As such, the half of the brain contralateral to the

56
00:03:31,440 --> 00:03:35,560
Speaker 1: hand is better in controlling fine motor movements. For example,

57
00:03:35,640 --> 00:03:39,480
Speaker 1: the left brain hemisphere in right handers. The strength of

58
00:03:39,480 --> 00:03:42,760
Speaker 1: this preference varies between individuals. Some people have a very

59
00:03:42,800 --> 00:03:46,280
Speaker 1: strong preference for one hand and resulting from that greater

60
00:03:46,360 --> 00:03:49,920
Speaker 1: issue in using the other for specific tasks. So it's

61
00:03:49,960 --> 00:03:54,080
Speaker 1: the brain that sets the barrier. But if the brain

62
00:03:54,120 --> 00:03:57,720
Speaker 1: sets the barrier, the brain can also remove it. Take

63
00:03:57,800 --> 00:04:01,640
Speaker 1: the case of Billy McLaughlin. McLoughlin is an award winning

64
00:04:01,640 --> 00:04:05,480
Speaker 1: guitarist known for a unique style of play, placing both

65
00:04:05,520 --> 00:04:09,040
Speaker 1: hands on the fretboard. He was originally predominantly a right

66
00:04:09,080 --> 00:04:12,160
Speaker 1: handed guitar player, but in the late nineteen nineties, but

67
00:04:12,240 --> 00:04:15,120
Speaker 1: despite having a record at number seven on the Billboard Charts,

68
00:04:15,160 --> 00:04:18,400
Speaker 1: he was struggling with control problems. He was missing notes

69
00:04:18,400 --> 00:04:21,200
Speaker 1: when he played, and experienced muscle spasms to the point

70
00:04:21,240 --> 00:04:24,880
Speaker 1: that he was unable to perform. Finally, in two thousand one,

71
00:04:25,120 --> 00:04:29,479
Speaker 1: McLoughlin was diagnosed with vocal dystonia, a movement disorder causing

72
00:04:29,520 --> 00:04:34,120
Speaker 1: muscles to contract involuntarily. Though advised to find another career,

73
00:04:34,440 --> 00:04:37,600
Speaker 1: McLoughlin opted to teach himself to play left handed, and

74
00:04:37,880 --> 00:04:43,240
Speaker 1: he succeeded. So this begs the question, can we teach

75
00:04:43,240 --> 00:04:47,320
Speaker 1: ourselves to become ambidextrous as adults. A two thousand seven

76
00:04:47,360 --> 00:04:50,040
Speaker 1: study found that as we age, we actually become more

77
00:04:50,040 --> 00:04:53,560
Speaker 1: ambidextrous without even trying, in part because the hand that

78
00:04:53,600 --> 00:04:57,440
Speaker 1: we use more loses its dominance. The study was small.

79
00:04:57,480 --> 00:05:01,480
Speaker 1: It included sixty participants, all wrongly right handed according to

80
00:05:01,520 --> 00:05:07,800
Speaker 1: the Edinburgh Handedness Inventory. The participants completed various computerized dexterity tests,

81
00:05:08,000 --> 00:05:12,800
Speaker 1: which included line tracing and aiming task and tapping. The

82
00:05:12,880 --> 00:05:16,000
Speaker 1: youngest group, average age twenty five years, performed all the

83
00:05:16,040 --> 00:05:20,120
Speaker 1: skills proficiently using their right hand. The middle aged participants,

84
00:05:20,160 --> 00:05:23,440
Speaker 1: average age fifty years, performed well using either hand on

85
00:05:23,480 --> 00:05:27,000
Speaker 1: the aiming task, while the two oldest groups, average ages

86
00:05:27,120 --> 00:05:30,400
Speaker 1: seventy and eighty years, performed just as well using either

87
00:05:30,480 --> 00:05:36,359
Speaker 1: hand on all tasks except one. However, overall performance appeared

88
00:05:36,360 --> 00:05:40,159
Speaker 1: to decline with increasing age, especially for the participants dominant

89
00:05:40,240 --> 00:05:44,440
Speaker 1: right hand, leading researchers to believe that quote we become

90
00:05:44,560 --> 00:05:47,839
Speaker 1: more ambidexterous as we get older because our dominant hand

91
00:05:47,960 --> 00:05:52,000
Speaker 1: loses its superior dexterity and becomes more like our weaker hand.

92
00:05:53,480 --> 00:05:56,640
Speaker 1: Some people have wondered whether attempting to become ambidexterous could

93
00:05:56,680 --> 00:06:00,000
Speaker 1: strengthen the brain and potentially slow or fight the effect

94
00:06:00,240 --> 00:06:04,960
Speaker 1: of aging or dementia. Aucklandberg said that's a myth. While

95
00:06:05,040 --> 00:06:07,320
Speaker 1: it is true in general that brain training is a

96
00:06:07,360 --> 00:06:10,160
Speaker 1: good idea when aging, research has shown that what gets

97
00:06:10,160 --> 00:06:13,560
Speaker 1: strengthened is what is trained. So if I trained to

98
00:06:13,640 --> 00:06:16,599
Speaker 1: write with my non dominant hand, this would affect the

99
00:06:16,640 --> 00:06:19,559
Speaker 1: motor brain areas of the contralateral half of the brain,

100
00:06:20,040 --> 00:06:23,680
Speaker 1: but not the areas involved in memory. Thus a specific

101
00:06:23,760 --> 00:06:31,080
Speaker 1: memory training would make more sense in aging and dementia.

102
00:06:31,960 --> 00:06:34,600
Speaker 1: Today's episode was written by Patty Resmusin and produced by

103
00:06:34,600 --> 00:06:37,120
Speaker 1: Tyler Clang. For more on this and lots of other topics,

104
00:06:37,200 --> 00:06:39,960
Speaker 1: visit how stuff works dot com. Brain Stuff is production

105
00:06:40,000 --> 00:06:42,479
Speaker 1: of I Heart Radio. For more podcasts my heart Radio,

106
00:06:42,600 --> 00:06:45,200
Speaker 1: visit the i heart Radio app, Apple Podcasts, or wherever

107
00:06:45,240 --> 00:06:46,520
Speaker 1: you listen to your favorite shows.