Understanding through Discussion


Welcome! You are not logged in. [ Login ]
EvC Forum active members: 114 (8751 total)
Current session began: 
Page Loaded: 05-27-2017 12:27 AM
121 online now:
Coyote, Dredge, DrJones*, ramoss (4 members, 117 visitors)
Chatting now:  Chat room empty
Newest Member: Roshankumar1234
Post Volume:
Total: 809,075 Year: 13,681/21,208 Month: 3,163/3,605 Week: 505/933 Day: 3/40 Hour: 3/0

Announcements: Reporting debate problems OR discussing moderation actions/inactions


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
1
23456
...
9Next
Author Topic:   Sexual Selection, Stasis, Runaway Selection, Dimorphism, & Human Evolution
RAZD
Member
Posts: 18472
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 3.8


Message 1 of 131 (201543)
04-23-2005 6:13 PM


This is cursory and a little simplified (no distinction between intra- and inter- sex selection) on purpose to keep it short (??) and to the point.

Sexual Selection


We have all heard about natural selection and survival of the fittest. Nature red in tooth and claw, etcetera.

There is another aspect of natural selection that is less well known and studied: sexual selection. Of late this seems to be getting more attention due to the problems with assigning species labels to organisms which can interbreed but don't. The reason they don't interbreed is not because they can't but because they don't "want" to -- the other organisms are not sexually attractive.

Obviously sexual selection occurs: in fact it occurs every time mating occurs. This may seem like an oxymoron but consider: if mating outside {group of organisms where interbreeding can occur} was frequent (a) it would be observed and (b) a lot of reproductive energy would be expended in an evolutionary pointless pursuit likely leading to extinction of species that so behaved compared to those that did not.

There is also a study that I remember reading about ~1975 in Canada where male stickleback fish were more likely to (attempt to) mate with objects that looked less and less like female stickleback fish the longer they had gone without mating activity. The study was mocked ("we needed to spend government money to find this out???") and so it was given wide publicity at the time. There is also evidence of this behavior in females too State-Dependent Mate-Assessment ... (click): "Mate-choice by females has been shown to be dependent on the state of the female, with females being less selective when limited by time or energy."

Sexual selection simply plays a role in choosing who to mate with and who not to mate with. There are many cases of closely related species that can produce hybrids but don't because they just don't mate.

Stasis


From (an abundance of) this kind of evidence one can conclude that sexual selection involves actively (whether consciously or not) choosing mates that best represent {the species icon} based on visual, olfactory and behavioral clues, where {the species icon} represents the "ideal mate" not just for the individual but for the population.

If we assume {the species icon} represents average values of features within the population, then in the absence of survival selection pressure within a species population, this active choice mechanism will lead to choosing the more "average" individuals for mates (and excluding the least normal individuals) whenever possible, a process that will essentially guarantee stasis within the species population.

This is observed in many species, and in humans there are several theories on the issue of "beauty" but one of the consistent factors involved is that the more beautiful faces are averaged (see average face-ness: click) -- more on this in humans later.

Mature populations without survival stress and without any other reason to {change\evolve} would more or less stabilize around an {average individual icon}.

Of course these individuals would also be healthy and well fit to the ecological niche they occupy, but the reason they are allowed to reproduce is because they are chosen as sexually suitable mates.

Run-away Selection


If we assume that {the species icon} does not represents an average value for any one (or more) {choice feature(s)} within the population, then in the absence of survival selection pressure within a species population, this active choice mechanism will lead to choosing the more "extreme" individuals displaying the desired feature(s) for mates (and excluding the more normal individuals) whenever possible, a process that will essentially guarantee transformation within the species population over time, until a point is reached where it can be taken no further. Mature populations without survival stress and without any other reason to {change\evolve} would trend towards an {extreme individual icon}, even to the point where species survival could be jeopardized: a species "fatal attraction" if you will.

The "run-away" aspect of this mating behavior develops because not only is the selection for individuals with the {choice feature(s)} but it is by individuals that prefer the {choice feature(s)}. Thus, to use a popular example of run-away sexual selection, not only does the male peacock have a large and extremely ornate tail, but the female peacock prefers males with the largest and most extremely ornate tail.

Richard Dawkins in The Blind Watchmaker also discusses an experiment with a long tailed bird where the male's long tail feathers were cut and then glued back with (1) shorter (2) same length and (3) longer tail feathers and then monitored for breeding success compared to (4) unmodified (control) males. There was no difference between group (2) and (4) (ie the effect of the glue process was eliminated as a variable), but the ones with the artificially long tail feathers were selected above the others: the sexual preference was for expression of the feature to an extent not seen within the population. Natural selection prevented the males from developing the longer tails after a certain point had been reached, but female preference was still for even longer tails.

Other studies have shown that long tail feathers (both male and female) do impose a definite survival disadvantage -- see Foraging cost (Behavioral Ecology Vol. 14 No. 4: 451456) for one.

Thus run-away selection -- in this case at least -- caused survival pressure to play a role when it otherwise didn't have to, in selection of mates.

The existence of species exhibiting extreme sexual selection -- peacocks, scissortail flycatchers, etcetera -- means either (a) they are on the way to extinction or (b) the selection also confers an advantage.

The advantage aspect is usually argued that only the most healthy, mature males could exhibit the full display, so selection for this feature is a short-hand for selecting healthy strong individual predisposed for survival. Certainly immature male peacocks do not have a full display (and have low reproduction success) and sickly or malnourished peacocks do not have as full and vibrant a display as their more healthy competition.

The identifying characteristics of run-away sexual selection, then, that differentiate it from normal sexual selection, involve a feature (or features) carried to an extreme that is not needed for species survival (and which may even jeopardize survival), and that may still be selected for if it were possible to undergo further (still continuing?) evolution.

This would be evident in a skewing of the population chosen for mates versus the variation within the population (demonstrating that it is one extreme end of available variations that is consistently chosen), and it would also be evident in comparison to closely related cousins without the features (demonstrating that the features are not needed for survival): all the longer tailed male birds mated, and close cousins do not have a long tail.

Mature populations without survival stress and without any other reason to {change\evolve} would be pulled away from an average value towards an {extreme individual icon}.

Of course these individuals would also be healthy and well fit to the ecological niche they occupy, but the reason they are allowed to reproduce is because they are chosen as sexually suitable mates.

Dimorphism


Survival of the fittest does not care about the sex of the individual, and for survival of a species to be optimized, both sexes need to survive to reproduce. Thus, at first glance one would expect that both sexes would be very similar in appearance and behavior, but this is not observed.

Sexual specialization is one reason that there is a difference between the sexes: often one sex raises the young and takes on the task of bringing them to a point of being able to take care of themselves. Thus in birds you see bright plumage in males, but dull and camouflaged coloration in females to better hide from predators. This does not, however, explain the bright plumage of the male (especially as there are many bird species where the coloration is the same for both sexes).

Run-away sexual selection easily explains the most extreme sexual dimorphisms in bird coloration and plumage displays, but it is not limited to just the most extreme examples. There are a lot of birds with red coloration, but it is difficult to get "redder" than a cardinal or a scarlet tanager.

There are also species where there is a large difference in {size\weight\strength}, and where the larger sex usually bullies the smaller one (and the smaller immature members of the same sex) in order to dominate sexually: gorillas, sea lions, hyenas, elk, etcetera.

These differences are not due to survival success, seeing as both sexes do survive, but due to sexual success: they are due to sexual selection. Bullies select themselves and deselect those rivals they can chase off, while "pretty" individuals are selected by those that find the individual "pretty" enough.

Run-away sexual selection usually involves a feature in one sex that is not expressed in the other (or that is incompletely expressed), with the result being a marked sexual dimorphism, but this does not mean that all sexual dimorphism is due to run-away sexual selection.

What the sexual dimorphism demonstrates when it is involved with a run-away sexual selection feature, is which sex is being selected for the feature: the peacock sex with the big tail is the sex where the tail is being selected to be big.

Human Evolution


Do humans exhibit any features that show the effects of run-away sexual selection: features that have no survival advantage, that may impose a survival burden, and where selection continues to push selection towards a skewed end of natural variation within the population?

Elsewhere I have discussed this, and have posted these features:
(a) Long head hair (longer than any other primate)
(b) Music\Dance\Artistic Creativity (more than any other primate)
(c) Sexual signal features (larger than any other primate)
(d) Skin hair thinness (more than any other primate)

I am not alone with this. See The mating mind: human sexual selection (click) for a discussion on the role of sexual selection in the evolution of the human brain size, complexity and ability -- with both pro and con arguments.

Long head hair certainly fits the "template" of run-away selection: it is extremely long compared to our cousins, beyond anything required for survival purposes alone, it would not be as long in immature males\females, it would not be lustrous in sickly or malnourished people, and it could lead to individuals being {noticed\caught\killed} by predators and other competitors. Long hair is still considered a marker of beauty (ie - sexual attraction): look at Fabio to say nothing of wigs that artificially lengthen hair. There is also sexual dimorphism in head hair with male facial hair exhibiting the same propensity for extreme length as the hair on top of both sexes exhibits, and this would indicate that this feature was selected in the males of the species (initially at least). This is also consistent with facial dimorphism in other primates.

Mating songs and dances are also common in other species, often exceeding any purpose that could be construed for survival alone, with the more creative individuals being selected for mating, presumably because creativity in song and dance also converts into creativity in survival. It would also exhibit health and fitness and maturity compared to other less fit competitors. This same behavior is seen in other species, but it is certainly not as well developed in other primates. That {Music\Dance\Artistic Creativity} ability it still selected for is apparent when you look at the superstars in the music world and other arts. There is little sexual dimorphism here (other than pitch of voice and small differences in flexibility and the like), and this could indicate that the ability of both sexes was important in the mating rituals (you also see this in other species, especially those that make long term pair bonding commitments).

Sexual "signal" features, such as round firm female breasts, well shaped buttocks and a large male penis. These features are not fully developed in either sex until puberty has been reached, and thus they signal readiness for mating. These features are important enough to people in general that a whole industries have been developed to cater to them: porn, breast implants, tight fitting pants, pants with pads for the less butt-endowed, etcetera. That these items are still being selected for hardly needs mentioning, but there is one thing worth noting and that is that both male and female features have been selected for augmented development: this is one case where sexual selection is not just from one sex choosing which of the other gets to reach for the brass ring on the merry-go-round as happens in some other species. There is, however, definite sexual dimorphism in the specific features involved, with the abundant female breast and buttock and the male penis.

Skin hair thinness -- the bareness of the human ape body is one of it's defining features because it is taken to extremes not seen in any other primate, even compared to sexual signaling patches of bare skin that develop in some species (notably in the buttocks and breast areas of the female while in estrus). Certainly there is no survival benefit to it: in every location where humans live they are accompanied by the domesticated dog, which is not at a survival disadvantage with his fur. The extent of human bareness on the other hand, has reached such an extreme condition that it requires compensatory behavior to live in most of those environments: clothes. There are also whole industries devoted to assisting people in divesting themselves of hair. There is no question that a barer body is {sexier\beautiful\attractive} when you look at the movies, art, and (of course) porn, particularly for the female. And this isn't just cultural, we have definite sexual dimorphism, particularly in the chest and buttock area, with the female being not only barer but more consistently bare.

In fact the link between enhanced female breast and buttock size and the increased female bareness in these specific areas indicates that these features were selected together: not just breast but bare breast, not just buttock but bare buttock.

There are also several other ape species where sexual readiness is signaled by bare areas on the female ... breast and buttocks. Note that the hair loss on and swelling of these areas occurs during estrus in the other apes, and thus it is an easily understood path for normal evolutionary operation in selection and development of a feature.

There are also other ape species that {can\do} extend estrus when in the presence of strange males. It is only in the human ape that these sexual signal features are displayed continuously, much beyond any need for survival or normal needs of a species for reproduction.

The question can also be investigated by what is considered beautiful (women) or handsome (men) and does it show a skewed pattern. This goes back to the average face issue raised above: "average face-ness" was not enough to fully explain the whole pattern in the experiment as there was also a clear bias in the data for youth (see babyface-ness: click), and the summary comments on this include these statements (read Summary: click for the whole summary):

(1) The results of our study are quite surprising. Compound (i.e. morphed) faces were, on average, regarded as being more attractive than the original faces. The more original faces one compound face consisted of, the higher its assigned attractiveness value. ... on the other hand, the attractiveness of the original faces included in a compound image itself influences the overall attractiveness of the compound face, i.e. the more attractive the original faces, the more attractive the resulting compound face. Thus, not simply the number, but also the attractiveness of the original faces influences the average attractiveness rating of compound faces. This result is in contrast to the 'attractiveness is averageness' hypothesis"

(2) For female faces, it could be shown that babyface attributes - such as large, round eyes, a large domed forehead and small, short nose and chin lead to a rise in attractiveness values. Only very few (9.5%) of the test subjects found the original adult faces most attractive. Most of the test subjects (90.5%) preferred faces with 10%-50% the proportions of the babyface scheme. This means: Even the most attractive female faces can become more attractive when their proportions are altered towards more babyfaceness.

(3) To sum up, our study shows clearly that the most attractive faces do not exist in reality, they are morphs, i.e. computer-created compound images you would never find in everyday live. These virtual faces showed characteristics that are unreachable for average human beings.

They also found "averaged" but not "babyfaced" beauty applied to males and thus it looks like human beauty involves both and (average individual icon} for many features and a skewed {extreme individual icon} tending towards idealized younger looking sexually mature females. That this also demonstrates the same pattern of run-away sexual selection noted for breasts, buttocks and bareness is not likely to be an accident.

{{edited main title to fit length restriction}}

This message has been edited by RAZD, 04*24*2005 04:06 PM

{{edited to match section subtitles to main title}}

This message has been edited by RAZD, 04*24*2005 06:46 PM

{{edited to add this ps: there are addendums to this post at:

Addendum #1 Message 41 - Human Body Hair and Female Pattern 'Bareness'
and
Addendum #2 Message 65 - Enabling Mechanisms
and
Addendum #3 Message 70 - Sweat it
and
Addendum #4 Message 71 - Final Words
end edit}}

This message has been edited by RAZD, 06*04*2005 06:51 PM

This message has been edited by RAZD, 06*11*2005 10:55 PM

Edited by RAZD, : on can


we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click)

Replies to this message:
 Message 2 by AdminJar, posted 04-23-2005 7:30 PM RAZD has responded
 Message 9 by macaroniandcheese, posted 04-24-2005 4:41 PM RAZD has responded
 Message 20 by EZscience, posted 04-27-2005 12:16 PM RAZD has responded
 Message 65 by RAZD, posted 06-02-2005 7:47 AM RAZD has acknowledged this reply
 Message 70 by RAZD, posted 06-04-2005 6:21 PM RAZD has acknowledged this reply
 Message 71 by RAZD, posted 06-11-2005 10:52 PM RAZD has responded

  
AdminJar
Inactive Member


Message 2 of 131 (201555)
04-23-2005 7:30 PM
Reply to: Message 1 by RAZD
04-23-2005 6:13 PM


Way too long for an OP
Can you pair it down to about 300 words or so max. State the basics, you can expand it as questions come up. It's an interesting subject but you're trying to get too much in the intial post.

Thanks.


New Members should start HERE to get an understanding of what makes great posts.

Comments on moderation procedures (or wish to respond to admin messages)? - Go to:
General discussion of moderation procedures
Thread Reopen Requests
Considerations of topic promotions from the "Proposed New Topics" forum

Other useful links:

Forum Guidelines, Style Guides for EvC and Assistance w/ Forum Formatting


This message is a reply to:
 Message 1 by RAZD, posted 04-23-2005 6:13 PM RAZD has responded

Replies to this message:
 Message 3 by RAZD, posted 04-23-2005 8:06 PM AdminJar has responded

  
RAZD
Member
Posts: 18472
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 3.8


Message 3 of 131 (201566)
04-23-2005 8:06 PM
Reply to: Message 2 by AdminJar
04-23-2005 7:30 PM


Re: Way too long for an OP
I think I want another admin to take this.
This message is a reply to:
 Message 2 by AdminJar, posted 04-23-2005 7:30 PM AdminJar has responded

Replies to this message:
 Message 4 by AdminJar, posted 04-23-2005 8:09 PM RAZD has responded

  
AdminJar
Inactive Member


Message 4 of 131 (201567)
04-23-2005 8:09 PM
Reply to: Message 3 by RAZD
04-23-2005 8:06 PM


Re: Way too long for an OP
No problem. I'm sure one of the other Admins will drop by soon. But near 3000 words is still too long for an OP.
This message is a reply to:
 Message 3 by RAZD, posted 04-23-2005 8:06 PM RAZD has responded

Replies to this message:
 Message 42 by RAZD, posted 05-13-2005 8:39 PM AdminJar has not yet responded

  
RAZD
Member
Posts: 18472
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 3.8


Message 5 of 131 (201709)
04-24-2005 12:43 PM


Admin comments please?
I have reviewed the OP and edited it some. unfortunately this has only made it a little longer as points were clarified.

I cannot at this time see a way to shorten it without gutting it in the process.

The only solution I can see is to post it in sections with each section subtitle currently in this post becoming the subtopic title.

This would mean posting the first section and then adding the others in order as replies to the first before any other replies were allowed.

An advantage of this approach is that it allows replies to address specific sections.


Replies to this message:
 Message 7 by AdminNosy, posted 04-24-2005 12:55 PM RAZD has responded

  
AdminNosy
Administrator
Posts: 4752
From: Vancouver, BC, Canada
Joined: 11-11-2003


Message 6 of 131 (201715)
04-24-2005 12:53 PM


Thread moved here from the Proposed New Topics forum.
  
AdminNosy
Administrator
Posts: 4752
From: Vancouver, BC, Canada
Joined: 11-11-2003


Message 7 of 131 (201717)
04-24-2005 12:55 PM
Reply to: Message 5 by RAZD
04-24-2005 12:43 PM


Re: Admin comments please?
I have promoted it as it is well done even if rather long for an OP.

I think you could have shortened it a lot by making each of the bolded sections a single sentence. Stating the point made but neither explaining them or supporting them.

Then subsequent posts could have supported and detailed each piece. Particularly is questions where asked.


This message is a reply to:
 Message 5 by RAZD, posted 04-24-2005 12:43 PM RAZD has responded

Replies to this message:
 Message 8 by RAZD, posted 04-24-2005 1:03 PM AdminNosy has not yet responded

  
RAZD
Member
Posts: 18472
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 3.8


Message 8 of 131 (201725)
04-24-2005 1:03 PM
Reply to: Message 7 by AdminNosy
04-24-2005 12:55 PM


Re: Admin comments please?
thank you sir.
This message is a reply to:
 Message 7 by AdminNosy, posted 04-24-2005 12:55 PM AdminNosy has not yet responded

  
macaroniandcheese 
Suspended Member (Idle past 1340 days)
Posts: 4258
Joined: 05-24-2004


Message 9 of 131 (201859)
04-24-2005 4:41 PM
Reply to: Message 1 by RAZD
04-23-2005 6:13 PM


i tried to discuss sexual selection here before. it didn't go over well. people couldn't get past the idea that hairy men are just attractive to some people and that their body hair couldn't possibly keep them warm.
This message is a reply to:
 Message 1 by RAZD, posted 04-23-2005 6:13 PM RAZD has responded

Replies to this message:
 Message 10 by RAZD, posted 04-24-2005 5:02 PM macaroniandcheese has responded

  
RAZD
Member
Posts: 18472
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 3.8


Message 10 of 131 (201871)
04-24-2005 5:02 PM
Reply to: Message 9 by macaroniandcheese
04-24-2005 4:41 PM


no surprise to me

hairy men are attractive to some women because the {skin bareness\hair thinness} is being selected for in females, and the expression in males is secondary, hence the much higher variability in hair thickness and coverage in males.


we are limited in our ability to understand
by our ability to understand

RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}


This message is a reply to:
 Message 9 by macaroniandcheese, posted 04-24-2005 4:41 PM macaroniandcheese has responded

Replies to this message:
 Message 11 by macaroniandcheese, posted 04-24-2005 5:48 PM RAZD has responded

  
macaroniandcheese 
Suspended Member (Idle past 1340 days)
Posts: 4258
Joined: 05-24-2004


Message 11 of 131 (201887)
04-24-2005 5:48 PM
Reply to: Message 10 by RAZD
04-24-2005 5:02 PM


?

in english?

anyways. that was just a specific example. i don't wanna get into this. bad taste since last time. i read jared diamond's third chimpanzee. i reccommend it. there's a big section on sexual selection.


This message is a reply to:
 Message 10 by RAZD, posted 04-24-2005 5:02 PM RAZD has responded

Replies to this message:
 Message 12 by RAZD, posted 04-24-2005 6:22 PM macaroniandcheese has responded
 Message 14 by RAZD, posted 04-24-2005 6:36 PM macaroniandcheese has responded

  
RAZD
Member
Posts: 18472
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 3.8


Message 12 of 131 (201897)
04-24-2005 6:22 PM
Reply to: Message 11 by macaroniandcheese
04-24-2005 5:48 PM


bareness is only important in females if that is where it is being selected for via sexual selection.

this means that males can range from as bare as females to as hairy as bonobos.

the reason males are bare is not because of selection for bareness in males, but because they inherit genes from the female parent that carry the bareness genes. over time males will trend towards being as bare as females, but they will lag behind (lustfully? :D) and will show greater variation in the levels of hairiness

jared is a good writer, have not seen that, thanks.


we are limited in our ability to understand
by our ability to understand

RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}


This message is a reply to:
 Message 11 by macaroniandcheese, posted 04-24-2005 5:48 PM macaroniandcheese has responded

Replies to this message:
 Message 13 by macaroniandcheese, posted 04-24-2005 6:33 PM RAZD has responded

  
macaroniandcheese 
Suspended Member (Idle past 1340 days)
Posts: 4258
Joined: 05-24-2004


Message 13 of 131 (201900)
04-24-2005 6:33 PM
Reply to: Message 12 by RAZD
04-24-2005 6:22 PM


but women participate in sexual selection as well. some women like hairy men, some don't. hairiness in men is not only a result of general familial hairiness. mostly, it is a result of expression of y chromosome traits. that is not affected by selection for non hairy females.
This message is a reply to:
 Message 12 by RAZD, posted 04-24-2005 6:22 PM RAZD has responded

Replies to this message:
 Message 15 by RAZD, posted 04-24-2005 6:40 PM macaroniandcheese has not yet responded

  
RAZD
Member
Posts: 18472
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 3.8


Message 14 of 131 (201901)
04-24-2005 6:36 PM
Reply to: Message 11 by macaroniandcheese
04-24-2005 5:48 PM


bad taste?
This message is a reply to:
 Message 11 by macaroniandcheese, posted 04-24-2005 5:48 PM macaroniandcheese has responded

Replies to this message:
 Message 16 by macaroniandcheese, posted 04-24-2005 6:41 PM RAZD has responded

  
RAZD
Member
Posts: 18472
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 3.8


Message 15 of 131 (201904)
04-24-2005 6:40 PM
Reply to: Message 13 by macaroniandcheese
04-24-2005 6:33 PM


see? it is the range of preferences in females that shows that bareness is not being preferentially selected in males.

the maintenance of hairy traits in the male chromosome also shows that bareness is not being preferentially selected in males.

the selection for hairy male faces on the other hand ... with the extra long growing facial hair show selection for that trait. and long head hair on both sexes could well be the result of that selection being carried forward from long ago.


we are limited in our ability to understand
by our ability to understand

RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}


This message is a reply to:
 Message 13 by macaroniandcheese, posted 04-24-2005 6:33 PM macaroniandcheese has not yet responded

  
1
23456
...
9Next
Newer Topic | Older Topic
Jump to:


Copyright 2001-2015 by EvC Forum, All Rights Reserved

™ Version 4.0 Beta
Innovative software from Qwixotic © 2017