McDougall's Experiment on Inheritance of Acquired Habits in Rats

William McDougall's experiment on the inheritance of acquired habits in rats has furnished strong evidence of the psychon theory, which is based on reincarnation of all organisms such as enzymes, living cells, animals and humans. The experiment was repeated by Crew and by Agar, Drummond & Tiegs in order to refute McDougall's results.

The experiment of Agar's group is more convincing than the one of Crew, because they took fewer (conscious or unconscious) precautions to prevent undesired results. For example Crew started the actual training of his rats only when they were 75 days old whereas McDougall and Agar's group began it when the rats were about 30 days old. (A2, p.167). It is a very reasonable assumption that the earlier the age at which the training begins, the more likely is any transmission of its effects.

The more the result of an experiment is contrary to expectations, the more convincing it is. Therefore I'll treat here the experiment of Agar's group who did not believe in Lamarckian inheritance, and not the experiment of McDougall which gave strong evidence of an increasing facility in learning the task of avoiding an illuminated gangway, even in the case of breeding from the slowest learners in each generation. Such an increasing facility in learning despite adverse selection has been found in several experiments and represents a complete refutation of Darwin's explanation of evolution.

The facility in learning the task is transmitted not through genes but through reincarnation. For an improvement in learning, it is necessary that the souls of the offspring are the souls of the rats which have done the experiment earlier. Souls are born with increased probability in similar conditions (environment continuity). The rats of all three experiments originated from the same pure Wistar stock of albino rats. That's why rats which immediately learned the task appeared much sooner in the two later experiments than in the first one.

In the Agar experiment, rats which originated from a single mating were divided into a trained and a control line. In the trained line all rats were trained and the next generations have only trained ancestors. In the control line the parents of the next generation were left untrained. All rats were marked and bred together with no discrimination of any sort. The group of Agar confirmed the improvement in learning found by McDougall. But there was a parallel improvement in the control line. As the rats of the control line only have untrained ancestors the thesis of McDougall that the improvement is the result of a Lamarckian inheritance is refuted.

The Agar group wants to give the impression that there are only periodical fluctuations in the rate of learning. But between generations 28 and 33 when the number of errors was increasing they made a succession of brother-sister matings (A3, S.116), and this is one of the methods by which Crew could prevent the undesired effect of a statistically relevant improvement in learning. Moreover they began to breed lots of rats in addition to the trained and the control line in order to test several hypotheses. For example they made a number of crosses between the two lines to examine the cumulated genetic differences between the lines. But the more rats are alive simultaneously, the higher is the proportion of rats which never or only rarely have done the experiment in former lives.

It is reasonable to assume a certain amount of fluctuation in the souls of the rats. The average rate of learning of all rats in each generation is not a satisfactory method to test the psychon thesis because the average is unduly affected by the appearance of rats which never or only rarely have done the experiment in former lives. Therefore only the ten quickest learners of the trained and the control line are considered in the following table. The third 'mean errors' column shows the mean errors of the ten quickest rats of both lines taken together.

The figures speak for themselves. If it had been possible for Agar's group to get results similar to the results of generations 14 - 28 with other untrained stocks, they certainly would have seized the opportunity to provide evidence of their claim that there is no progressive improvement but only fluctuations in the rate of learning. McDougall's stocks of control indicate that it is not possible to get such results in the first generations of (different) untrained stocks (M4, S.326).

M4: McDougall (1938), Fourth report on a Lamarckian experiment, Brit. J. Psychol. 28, 321-345
A2: Agar, Drummond & Tiegs (1942), Second report on a test of McDougall's experiment , J. Exp. Biol. 19, 158-167
A3: Agar, Drummond & Tiegs (1948), Third report on a test of McDougall's experiment , J. Exp. Biol. 25, 103-122
A4: Agar, Drummond, Tiegs & Gunson (1954), Fourth report on a test of McDougall's experiment , J. Exp. Biol. 31, 307-321

 

Gene-ration

Number of rats

*

Mean errors

Mean errors

Mean errors

2.

15

21

24

28

28

34

38

40

40

42

46

34.1

29.6

7

24

30

35

36

36

37

56

36.3

3.

25

11

14

20

25

26

30

32

32

35

36

26.1

21.0

24

17

20

22

27

28

29

32

33

34

39

28.1

4.

19

18

18

19

20

23

24

24

25

27

31

22.9

18.2

23

12

15

18

18

21

27

28

29

29

30

22.7

5.

22

2

21

24

25

27

31

31

34

35

39

26.9

22.5

20

17

23

28

29

29

32

32

35

35

35

29.5

6.

22

18

19

20

20

24

26

29

29

29

30

24.4

12.4

22

3

5

8

9

13

13

17

19

20

22

12.9

7.

31

0

3

16

16

18

18

19

19

19

23

15.1

11.2

33

8

9

11

15

16

21

21

21

24

24

17.0

8.

41

1

6

8

10

17

18

19

19

20

22

14.0

8.5

16

3

4

6

13

17

18

21

24

24

27

15.7

9.

12

1

2

2

5

6

12

16

20

21

25

11.0

7.3

47

4

12

14

15

17

18

19

20

21

21

16.1

10.

13

2

16

18

18

19

19

19

21

26

27

18.5

15.0

37

12

14

15

17

19

20

21

22

25

25

19.0

11.

44

5

8

8

10

12

15

16

16

16

17

12.3

7.2

60

5

6

6

6

8

10

10

11

13

16

9.1

12.

36

3

14

20

20

20

21

21

23

24

24

19.0

5.3

33

3

3

3

4

5

6

6

7

13

13

6.3

13.

38

2

3

4

5

8

9

10

10

10

10

7.1

7.1

11

10

10

24

26

30

31

36

38

40

141

38.6

14.

50

1

1

2

2

2

2

3

3

3

4

2.3

2.2

37

3

3

4

5

5

5

5

6

6

7

4.9

15.

49

1

3

4

5

6

7

8

8

8

8

5.8

4.5

50

4

5

5

6

6

7

8

9

11

11

7.2

16.

50

3

3

4

4

5

5

6

9

10

11

6.0

3.4

50

2

2

2

4

5

5

6

6

6

7

4.5

17.

80

0

0

1

1

2

2

2

2

3

3

1.6

1.3

50

1

2

2

3

4

4

4

4

7

8

3.9

18.

50

0

6

8

9

12

14

15

15

16

17

11.2

6.2

50

3

4

6

8

9

9

10

14

14

16

9.3

19.

50

0

1

1

2

2

3

5

5

5

7

3.1

1.6

50

1

2

2

2

5

6

6

6

6

7

4.3

20.

50

0

5

6

6

7

8

12

12

12

13

8.1

2.2

50

0

0

1

2

3

3

3

5

7

7

3.1

21.

50

0

2

2

2

3

3

6

7

9

10

4.4

1.9

34

0

2

2

3

4

4

5

5

5

5

3.5

22.

48

0

0

0

0

0

0

0

0

1

1

0.2

0.1

50

0

1

1

3

3

4

5

6

6

10

3.9

23.

49

0

0

2

3

3

4

4

5

5

6

3.8

2.3

50

0

3

4

6

9

10

10

10

11

12

7.5

24.

50

0

2

4

6

6

9

10

12

13

13

7.5

1.9

49

0

1

2

2

2

3

3

4

5

5

2.7

25.

50

0

0

0

1

1

1

1

2

3

4

1.3

1.1

50

2

3

3

6

7

9

9

9

10

10

7.8

26.

50

1

2

2

2

4

4

5

5

5

5

3.5

3.4

50

4

5

5

6

6

6

6

7

7

7

4.9

27.

39

1

2

3

3

4

4

5

5

5

5

3.7

3.2

50

3

4

4

4

4

5

5

6

6

6

4.7

28.

50

0

0

1

1

1

1

2

3

3

4

1.6

1.6

47

4

5

6

6

6

7

8

8

8

8

6.6

 

* Number of errors of the best 10 rats of the trained line (first line) and control line (second line)


Some quotations

 

"His (McDougall's) principal evidence of Lamarckian inheritance is comprised in the following facts:

1) There has been a progressive - though irregular - decline in the average number of errors per generation; a very marked decline in the number of errors made by the best rat of each generation; and a less certain decline in the number of errors made by the worst rat.

2) McDougall found, as we have, that his rats showed a slight initial preference for the bright passage. In the later generations both of the main experiment, and of the experiment in which training was combined with adverse selection, this was turned into a pronounced preference of the dim passage. ...

3) He found an improvement, irregularly progressive through 14 generations of an experiment in which training was combined with adverse selection (breeding from the slowest learners in each generation). The improvement in this stock was immediate and its rate actually faster than in the main experiment in spite of the adverse selection.

4) Seven groups of control rats, four of them being, like his trained rats, of Wistar Institute stock, all gave average number of errors much higher than the highest average in generations 13 - 34 of the trained stock. The slower rates of learning of these controls are also shown by comparison of the best and the worst rat of each group with the similar figures for the trained stock." (Agar, Drummond & Tiegs, 1935, A FIRST REPORT ON A TEST OF McDOUGALL'S LAMARCKIAN EXPERIMENT ON THE TRAINING OF RATS, J. Exp. Biol. 12, p.209)

 

"I confess I have been surprised to see this state of affairs evolving, for the 12 original rats were out of an intensely inbred stock and, according to current genetic thought, ought to have been exceedingly similar one to the other in respect of genetical constitution. They were out of a stock that had undergone prolonged gene purgation, and yet the history of my stock reads like an experiment in inbreeding. There is a broad base of family lines and a narrow apex of two remaining lines. The reproductive rate falls, and line after line becomes extinct. Agar is wise in avoiding such close inbreeding as I have practised." (A Repetition of McDougall's Lamarckian Experiment, 1936, by F. A. E. Crew, J. Genet. 33, p.75)

 

"Tryon has bred rats selectively according to their ability on the California automatic maze, and, in a very carefully controlled experiment, has shown clearly that the offspring of 'bright' parents contain more 'brights' than 'dulls', and that the offspring of 'dulls' more 'dulls' than 'brights'. The interesting point here in connection with Lamarckian inheritance, however, is that both strains, 'dulls' as well as 'brights', became progressively better at learning this maze.
...
McDougall and Tryon have obtained evidence of an increased facility on a specific task with successive, trained generations; Crew and Agar, under conditions resembling McDougall's, have obtained no such evidence. The reasons for this discrepancy are not clear from the published accounts." (
Nature, Feb. 4, 1939, Vol. 143, p.190)


Further discussion

Three well-known mechanisms and a less well-known mechanism have been proposed to explain the fact that animal species are able to change their behavior in order to survive:

1.      The inheritance of acquired habits of Jean-Baptiste Lamarck.

2.      The selection theory of Charles Darwin

3.      The morphogenetic fields of Rupert Sheldrake

4.      The psychon thesis (animal reincarnation)

The inheritance of acquired habits cannot explain the increasing facility in learning of the control line rats which have no trained ancestors. The selection theory is disproved by the experiments with adverse selection. The fact that rats of other stocks did not improve in learning is not consistent with the theory of morphogenetic fields as proposed by Rupert Sheldrake.

So the only reasonable explanation of McDougall's experiment seems to be the psychon thesis. All facts are consistent with this reincarnation theory.


Discussions concerning McDougall's experiment:

         Psycho-Lamarckism versus Darwinism (Weismann's experiment, dog tail dogging)

         Lamarckism & Adverse Selection Experiments


Highly recommended:  Rat Learning and Morphic Resonance  by Rupert Sheldrake

"In mechanistic biology, a sharp distinction is drawn between innate and learned behaviour: the former is assumed to be 'genetically programmed' or 'coded' in the DNA, while the latter is supposed to result from physical and chemical changes in the nervous system."


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